msm: mdss: update layer mixer access for calibration tool

Calibration tool should have register access on all layer
mixers connected to DSPP pipe and WB path. It should
also have control layer register access to read
the current layer mixer configuration.

Change-Id: If2cc86c2e6f470e090746a400b16cb540948c3e9
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>