[media] v4l: s5p-tv: hdmi: fix mode synchronization

The mode setup was applied on HDMI hardware only on resume event.  This caused
problem if HDMI was not suspended between mode switches.  This patch fixes this
problem by setting a dirty flag on a mode change event.  If flag is set, then
new mode is applied on the next stream-on event.

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