This patch adds i.MX8qm LDB support.
Logics are added to make i.MX8qm LDB cope with Mixel LVDS PHY.
Also, logics are added to handle pixel link padding quirks for i.MX8qm LDB.

Signed-off-by: Liu Ying <victor.liu@nxp.com>
(cherry picked from commit d8e089c7)