msm: vidc: Fix NULL pointer exception

The error check to validate the device open failure has an
issue where it is checking the wrong variable. This lead
to NULL pointer access. This change fixes the same.

CRs-Fixed: 417092
Change-Id: I635fc43b19a368c2477ab41c9d6d28ec9dc8524e
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>