IB/hfi1: Rename exp_lock to exp_mutex

The mutex exp_lock in struct hfi1_ctxtdata is used to protect all
Expected TID data of a user context. This patch renames it to exp_mutex
to better reflect its identity and prepare for upcoming patches.

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/hfi1/hfi.h

@@ -245,8 +245,8 @@ struct hfi1_ctxtdata {
 	struct exp_tid_set tid_used_list;
 	struct exp_tid_set tid_full_list;
 
-	/* lock protecting all Expected TID data */
-	struct mutex exp_lock;
+	/* lock protecting all Expected TID data of user contexts */
+	struct mutex exp_mutex;
 	/* per-context configuration flags */
 	unsigned long flags;
 	/* per-context event flags for fileops/intr communication */