V4L/DVB (4936): Make MT4049FM5 tuner to set FM Gain to Normal

- remove any specific TDA9887_SET_CONFIG of usbvision driver
- add fm_gain_normal=1 to the MT4049FM5 tuner for radio functionality

Signed-off-by: Thierry MERLE <thierry.merle@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>