msm: Address warnings and review comments for ais

Fix the error path cleanup of mapping info structure.
Remove unnecessary WARN_ON usages in camera code.
This patch also fixes buffer enqueue memory leak.

Change-Id: I2ab5861c9f96a454fd03b36b69814cd8af0cebfd
Signed-off-by: Terence Ho <terenceh@codeaurora.org>