locking/ww_mutex: Fix acquire/release imbalance in ww_acquire_init()/ww_acquire_fini()

In ww_acquire_init(), mutex_acquire() is gated by CONFIG_DEBUG_LOCK_ALLOC.
The dep_map in the ww_acquire_ctx structure is also gated by the
same config. However mutex_release() in ww_acquire_fini() is gated by
CONFIG_DEBUG_MUTEXES. It is possible to set CONFIG_DEBUG_MUTEXES without
setting CONFIG_DEBUG_LOCK_ALLOC though it is an unlikely configuration.
That may cause a compilation error as dep_map isn't defined in this
case. Fix this potential problem by enclosing mutex_release() inside
CONFIG_DEBUG_LOCK_ALLOC.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210316153119.13802-3-longman@redhat.com