vidc: 1080p: Reset meta data offset to zero

For multi-resolution clips, the meta data offset used while
doing cache clean of meta data buffer is from the previous
resolution & resulting in kernel panic. Resetting the offset
to zero during meta data buffer initialization for new
resolution fixes the issue.

Change-Id: I06b20e10efc837fcfe44f532e90293734b4d2df8
CRs-fixed: 386245
Signed-off-by: Rajeshwar Kurapaty <rkurapat@codeaurora.org>