msm: mdss: provide an exclusive access to QSEED2 block

Calibration tool and pp module uses the QSEED2 block on
VIG pipe to set the sharpness. This sharpness effect
is overwritten when both modules tries to update it
at the same time. Hence, it is required to provide
an exclusive access to QSEED2 block when target is in
display tuning mode.

Change-Id: I41b85313e529a3cca70de7e652c3abb7d4defbca
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>