msm: vidc: Do sanity check for different IOCTL cmd

Wrong buffer length or buffer type sent by V4L2 client
is not handled properly in V4L2 framework, which results
in page fault situation in different IOCTL functions
like prepare buf. Do a sanity check for the same.

Change-Id: I795076e8f7fc6d511eb728f44cd50015e704ffa1
Signed-off-by: Pushkaraj Patil <ppatil@codeaurora.org>