scsi: bnx2fc: Add missing annotation for bnx2fc_abts_cleanup()

Sparse reports the following warning:

  warning: context imbalance in bnx2fc_abts_cleanup() - unexpected unlock

The root cause is the missing annotation at bnx2fc_abts_cleanup(). Add the
missing __must_hold(&tgt->tgt_lock) annotation.

Link: https://lore.kernel.org/r/20200411001933.10072-8-jbi.octave@gmail.comSigned-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/bnx2fc/bnx2fc_io.c

@@ -1081,6 +1081,7 @@ int bnx2fc_eh_device_reset(struct scsi_cmnd *sc_cmd)
 }
 
 static int bnx2fc_abts_cleanup(struct bnx2fc_cmd *io_req)
+	__must_hold(&tgt->tgt_lock)
 {
 	struct bnx2fc_rport *tgt = io_req->tgt;
 	unsigned int time_left;