drm: EDID accept separate sync video mode

X is accepting such video mode, do the same. Pointed out by Joshua Roys
on IRC. Fix https://bugzilla.redhat.com/show_bug.cgi?id=540024



[fix printf to use composite not integrated :- airlied]

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>