msm: vidc: correct ion flags for CP_CAMERA_ENCODE context bank

if CP_CAMERA_ENCODE context bank enabled, ION_FLAG_CP_PIXEL ion flag
should be replaced with  ION_FLAG_CP_CAMERA_ENCODE, otherwise mapping
would fail.

Change-Id: I8fdbc91dc00f498c0a7f1af1cd258c5273299097
Signed-off-by: Sayantan Majumder <smajumde@codeaurora.org>
Signed-off-by: UtsavBalar1231 <utsavbalar1231@gmail.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>