[media] cx25840: fill the media controller entity

Instead of keeping the media controller entity not initialized,
fill it and create the pads for cx25840.

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

diff --cc drivers/media/i2c/cx25840/cx25840-core.c
Simple merge

diff --cc drivers/media/i2c/cx25840/cx25840-core.h
Simple merge