msm: camera: isp: Fix for incorrect reg update on PIX

In case of dual VFE and RDI path is enabled, RDI reg update
should not interefere with PIX path. But due to incorrect
reg update written to hardware, it is resulting in line
noise or split patterns. Correction made in reg update
programming.

Change-Id: I43fde4fe11d75e4a4d3d883f144497748d3073f6
Signed-off-by: Sagar Gore <sgore@codeaurora.org>