msm: isp: Avoid unaligned register access

Unaligned register access will reslut in device
crash. Avoid them by checking the register address
before accessing them.

Same as (Ib58efa2a68115ec9929b9270c123c904737196ee)

CRs-Fixed: 1001412
Change-Id: Iaf9201421f4e9abd03997b4ac6f08fdbe7c69515
Signed-off-by: Abhishek Kondaveeti <akondave@codeaurora.org>
Signed-off-by: VijayaKumar T M <vtmuni@codeaurora.org>