isdn: eicon: fix sparse warning: make global functions static

Fix this sparse warnings by making the functions static:

  drivers/isdn/hardware/eicon/di.c:356:6: warning: symbol 'isdn_rc' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/di.c:558:6: warning: symbol 'isdn_ind' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:595:6: warning: symbol 'api_parse' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:634:6: warning: symbol 'api_save_msg' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:666:6: warning: symbol 'api_load_msg' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:3417:6: warning: symbol 'manufacturer_req' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:3745:6: warning: symbol 'manufacturer_res' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:4077:6: warning: symbol 'control_rc' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:4743:6: warning: symbol 'data_rc' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:4779:6: warning: symbol 'data_ack' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:4805:6: warning: symbol 'sig_ind' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:6173:6: warning: symbol 'SendInfo' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:6349:6: warning: symbol 'SendMultiIE' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:6468:6: warning: symbol 'nl_ind' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:7250:6: warning: symbol 'get_plci' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:7409:6: warning: symbol 'add_d' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:7427:6: warning: symbol 'add_ai' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:7448:6: warning: symbol 'add_b1' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:7912:6: warning: symbol 'add_b23' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:8709:6: warning: symbol 'nl_req_ncci' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:8731:6: warning: symbol 'send_req' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:8866:6: warning: symbol 'listen_check' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:8909:6: warning: symbol 'IndParse' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:8994:6: warning: symbol 'ie_compare' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:9003:6: warning: symbol 'find_cip' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:9071:6: warning: symbol 'SetVoiceChannel' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:9089:6: warning: symbol 'VoiceChannelOff' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:9102:6: warning: symbol 'AdvCodecSupport' was not declared. Should it be static?
  drivers/isdn/hardware/eicon/message.c:9198:6: warning: symbol 'CodecIdCheck' was not declared. Should it be static?

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>