msm: vidc: Check for valid packet attributes

Packet size received from firmware should be valid and
should be less than the queue size. Also, the read index
should be valid.

CRs-fixed: 479225
Change-Id: Ie0c5db3f4b696f1c43810838435874703b40b54f
Signed-off-by: Vinay Kalia <vkalia@codeaurora.org>