media: staging: bcm2835-camera: use V4L2_FRACT_COMPARE

Now the equivalent of FRACT_CMP() is added in v4l2 common internal API
header.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>