[media] s5p-tv: fix mbus configuration

This patch fixes mbus configuration between Mixer, SDO and HDMI.  The SDO
accepts only YUV444 on input. The HDMI in DVI mode accepts only RGB888. Now
Mixer is choosing proper output format depending on mbus format.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>