msm: ais: cpp changes to validate ioctl input

When the Camera application exercises the  V4L2  ioctl operations, CPP
driver would attempt to the copy  user space buffer  contents into the
internal kernel buffer.  If an invalid length of the user space buffer
is passed onto the driver, it could trigger buffer overflow condition.
Thus, fix this by copying user space buffer contents into kernel space
buffer of the  driver for further processing, only after checking for
proper length of user space buffer.

Change-Id: I0386d0f84a8d7015bfe6bbb1e9472fa8934df83a
CRs-Fixed: 2025367
Signed-off-by: Rahul Sharma <sharah@codeaurora.org>