[media] s5p-fimc: Fix output DMA handling in S5PV310 IP revisions

FIMC IP in S5Pv310 series has extended DMA status registers
and some bit fields are marked as reserved comparing to S5PC100/110.
Use correct registers for getting DMA write pointer in each SoC variant
supported by the driver.

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>