[media] v4l: s5p-mfc: Fix default pixel format selection for decoder

The patch adding the v6 version of MFC changed the default format for
the CAPTURE queue, but this also affects the v5 version. This patch
solves this problem by checking the MFC version before assigning the
default format.

Signed-off-by: Kamil Debski <k.debski@samsung.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>