drm/i915: Add support for Video Burst Mode for MIPI DSI

v2: Updated the error log as suggested by Imre

Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>