msm: mdss: Fix the incorrect address base for postproc calib ioctl

The postproc calib configuration address should always offset form
MDSS base, not MDP base. Also allow postproc calib ioctl to access
the MDSS version register.

Change-Id: I9dbf5a2a75a0a384e7f97efca49f1a75e5d01fc8
Signed-off-by: Ping Li <quicpingli@codeaurora.org>