[media] saa7164: get rid of warning: no previous prototype

drivers/media/pci/saa7164/saa7164-api.c:1489:5: warning: no previous prototype for 'saa7164_api_modify_gpio' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-api.c:168:5: warning: no previous prototype for 'saa7164_api_set_gop_size' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-api.c:622:5: warning: no previous prototype for 'saa7164_api_set_dif' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-api.c:825:5: warning: no previous prototype for 'saa7164_api_configure_port_vbi' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-api.c:861:5: warning: no previous prototype for 'saa7164_api_configure_port_mpeg2ts' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-api.c:895:5: warning: no previous prototype for 'saa7164_api_configure_port_mpeg2ps' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-api.c:928:5: warning: no previous prototype for 'saa7164_api_dump_subdevs' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-bus.c:109:6: warning: no previous prototype for 'saa7164_bus_dumpmsg' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-bus.c:84:6: warning: no previous prototype for 'saa7164_bus_verify' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-cmd.c:135:5: warning: no previous prototype for 'saa7164_cmd_dequeue' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-cmd.c:189:5: warning: no previous prototype for 'saa7164_cmd_set' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-cmd.c:262:5: warning: no previous prototype for 'saa7164_cmd_wait' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-cmd.c:26:5: warning: no previous prototype for 'saa7164_cmd_alloc_seqno' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-cmd.c:45:6: warning: no previous prototype for 'saa7164_cmd_free_seqno' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-cmd.c:57:6: warning: no previous prototype for 'saa7164_cmd_timeout_seqno' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-cmd.c:67:5: warning: no previous prototype for 'saa7164_cmd_timeout_get' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-encoder.c:1104:29: warning: no previous prototype for 'saa7164_enc_next_buf' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-encoder.c:1290:5: warning: no previous prototype for 'saa7164_g_chip_ident' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-encoder.c:1300:5: warning: no previous prototype for 'saa7164_g_register' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-encoder.c:1313:5: warning: no previous prototype for 'saa7164_s_register' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-fw.c:40:5: warning: no previous prototype for 'saa7164_dl_wait_ack' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-fw.c:56:5: warning: no previous prototype for 'saa7164_dl_wait_clr' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-fw.c:74:5: warning: no previous prototype for 'saa7164_downloadimage' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-vbi.c:1050:29: warning: no previous prototype for 'saa7164_vbi_next_buf' [-Wmissing-prototypes]
drivers/media/pci/saa7164/saa7164-vbi.c:987:5: warning: no previous prototype for 'saa7164_vbi_fmt' [-Wmissing-prototypes]

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>