msm: camera: cpp: Fixing Heap overflow in output buffer

Issue:
Missing bound check when writing into the output array
buffer, which can lead to out-of-bound heap write.

Fix:
Addding hardcoded constant 8 in the MSM_OUTPUT_BUF_CNT
macro and size check to the place where the array is
accessed. Returning '0' if exceeds MSM_OUTPUT_BUF_CNT.
Caller will return -EINVAL for '0'.

Change-Id: Ic03f86e3e47ece9ca7069527e741a75ad9a0f83f
CRs-Fixed: 2004036
Signed-off-by: Pratap Nirujogi <pratapn@codeaurora.org>