drm/vmwgfx: Perform topology validation during atomic modeset.

This patch adds display (primary) memory validation during modeset
check. Display memory validation are applicable to both SOU and STDU,
so allow both display unit to undergo this check.

Also added check for SVGA_CAP_NO_BB_RESTRICTION capability which lifts
bounding box restriction for STDU.

Signed-off-by: Deepak Rawat <drawat@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>