[media] saa7115: Implement i2c_board_info.platform_data

This patch implements i2c_board_info.platform_data, and some options to
override the default initialization table for the GM7113C and SAA7113
chips.

Signed-off-by: Jon Arne Jørgensen <jonarne@jonarne.no>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>