Fix QAT allocation failure return value

When qat_compress() fails to allocate the required contiguous memory
it mistakenly returns success. This prevents the fallback software
compression from taking over and (un)compressing the block.

Resolve the issue by correctly setting the local 'status' variable
on all exit paths. Furthermore, initialize it to CPA_STATUS_FAIL
to ensure qat_compress() always fails safe to guard against any
similar bugs in the future.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #9784
Closes #9788