[media] s5p-fimc: Add support for ISP Writeback data input bus type

A second sink pad is added to each FIMC.N subdev that will be used
to link it to the FIMC-IS-ISP subdev. Only V4L2_MBUS_FMT_YUV10_1X30
format is supported at this pad (FIMC_SD_PAD_SINK_FIFO).
The routine checking for mismatch in the image formats at sides of
the links is updated to account for the fact FIMC.X subdevs now have
sink pads at the pad indexes 0, 1 and source pad at pad index 2.
If link to FIMC.X pad 1 is activated we switch FIMC input data bus
type to the ISP Writeback. Only a single active link to FIMC.X pad 0
or 1 will be allowed at any time.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>