zbd: relocate Coverity annotation

zbd: relocate Coverity annotation

The Coverity annotation added earlier to suppress a false positive
about missing unlock in zbd_adjust_block() didn't work because it
was placed not before the return statement, but earlier in the code.

Move the annotation to the right place to avoid the warning.

Reported-by: Bart Van Assche <bvanassche@acm.org>
Fixes: 8e4b2e55512f("zbd: don't unlock zone mutex after verify replay")
Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>