drm/i915: set the VIC of the mode on the AVI InfoFrame

We currently set "0" as the VIC value of the AVI InfoFrames. According
to the specs this should be fine and work for every mode, so to my
point of view we can't consider the current behavior as a bug. The
problem is that  we recently received a bug report (Kernel bug #50371)
from a user that has an AV receiver that gives a black screen for any
mode with VIC set to 0.

So in order to make at least some modes work for him, this patch sets
the correct VIC number when sending AVI InfoFrames.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=50371


Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>