msm: camera: isp: process RDI regupdate from each ISP

with dual_isp_sync enabled pix path regupdate can be processed
with interrupt from dual_isp_sync irq. however RDI dual only
one ISP. So regupdate irq need to be processed from each ISP.

Change-Id: Iff0c397ee8e21784b1bf994482bb575c0482b8cb
Signed-off-by: Srikanth Uyyala <suyyala@codeaurora.org>