block: remove test of incorrect io priority level

Ever since commit eca2040("scsi: block: ioprio: Clean up interface
definition"), the macro IOPRIO_PRIO_LEVEL() will mask the level value to
something between 0 and 7 so necessarily, level will always be lower than
IOPRIO_NR_LEVELS(8).

Remove this obsolete check.

Reported-by: Kexin Wei <ys.weikexin@h3c.com>
Cc: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20250508083018.GA769554@bytedance
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/ioprio.c

@@ -46,12 +46,8 @@ int ioprio_check_cap(int ioprio)
 			 */
 			if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE))
 				return -EPERM;
-			fallthrough;
-			/* rt has prio field too */
-		case IOPRIO_CLASS_BE:
-			if (level >= IOPRIO_NR_LEVELS)
-				return -EINVAL;
 			break;
+		case IOPRIO_CLASS_BE:
 		case IOPRIO_CLASS_IDLE:
 			break;
 		case IOPRIO_CLASS_NONE: