[media] s5p-fimc: Refactor hardware setup for m2m transaction

Remove redundant H/W setup logic by merging fimc_prepare_config()
and the device_run() callback.

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>