libipw: correct sparse warnings and mark some variables static

  CHECK   drivers/net/wireless/ipw2x00/libipw_module.c
drivers/net/wireless/ipw2x00/libipw_module.c:65:21: warning: symbol 'libipw_config_ops' was not declared. Should it be static?
drivers/net/wireless/ipw2x00/libipw_module.c:66:6: warning: symbol 'libipw_wiphy_privid' was not declared. Should it be static?
  CHECK   drivers/net/wireless/ipw2x00/libipw_wx.c
drivers/net/wireless/ipw2x00/libipw_wx.c:415:17: warning: symbol 'ssid' shadows an earlier one
drivers/net/wireless/ipw2x00/libipw_wx.c:324:9: originally declared here

Signed-off-by: John W. Linville <linville@tuxdriver.com>