target/user: Fix a data type in tcmu_queue_cmd()

This patch avoids that sparse reports the following error messages:

drivers/target/target_core_user.c:547:13: warning: incorrect type in assignment (different base types)
drivers/target/target_core_user.c:547:13:    expected int [signed] ret
drivers/target/target_core_user.c:547:13:    got restricted sense_reason_t
drivers/target/target_core_user.c:548:20: warning: restricted sense_reason_t degrades to integer
drivers/target/target_core_user.c:557:16: warning: incorrect type in return expression (different base types)
drivers/target/target_core_user.c:557:16:    expected restricted sense_reason_t
drivers/target/target_core_user.c:557:16:    got int [signed] ret

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>

drivers/target/target_core_user.c

@@ -537,7 +537,7 @@ tcmu_queue_cmd(struct se_cmd *se_cmd)
 	struct se_device *se_dev = se_cmd->se_dev;
 	struct tcmu_dev *udev = TCMU_DEV(se_dev);
 	struct tcmu_cmd *tcmu_cmd;
-	int ret;
+	sense_reason_t ret;
 
 	tcmu_cmd = tcmu_alloc_cmd(se_cmd);
 	if (!tcmu_cmd)