drm/i915: Enable RANDOM resolution support for MIPI panels

Some MIPI panels might not have resolution which is a multiple of 64 like
1366x768. Enable this feature for such panels by default

Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>