video: msm: Remove adjustment to MDP revision

Remove the modification of mdp_rev during mdp_probe. Not needed since
board files now have the correct MDP revision data.

CRs-Fixed: 417080
Change-Id: I553cb2a8e8de43b6c7b7976c3eca67d00a3cfe4f
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>