Implement BOARD_CAMERA_NO_UNWANTED_MSG

On msm7x27 devices, most camera hals appear to spam this message:

lockIfMessageWanted(16): dropped unwanted message

This happens for all camera modes except barcode scanning. If there
is a better fix for this issue, please let me know.

Change-Id: I266c6d21196c193e389e6773d532591df7b3534a