block: Fix mismerge in queue freeze logic

block: Fix mismerge in queue freeze logic

Commit 7466bf8e2078 ("blk-mq: fix freeze queue race") introduced a mutex
to protect the queue freeze/unfreeze logic.

The locking requirement was obsoleted by commit c03fa711de6a ("block:
use an atomic_t for mq_freeze_depth") but the mutex was left in place in
our backport.

During the c311ca8a3d93 merge of the pmem tree conflicts arose in
blk-mq. The mutex lock calls were removed but the mutex unlocks left in
place. This lead to NVMe controller reset failures in ED testing. Remove
the last remnants of commit 7466bf8e2078.

Orabug: 26254388

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Ashok Vairavan <ashok.vairavan@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>