msm: mdss: Move histogram addr and interrupt setup to hist init

Currently, the histogram register address and the hist interrupt
bit shift were initialized during hist_enable. However, these values
are needed earlier in histogram info initialization. These values
are now initialized when the hist_info structures are allocated.

Change-Id: Ic82fa3da479b59b88bca5aae6f04b32f97182bc3
Signed-off-by: Benet Clark <benetc@codeaurora.org>