msm: camera2: cpp: Fix out-of-scope pointer variable

The variable used for compat ioctl is having local scope.
This results in invalid pointer access resulting in random
crash.

Change-Id: I120b7cb6ced31d9e41555c4991cbf15b759c8a04
Signed-off-by: Rajakumar Govindaram <rajakuma@codeaurora.org>