Revert "block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE"

This reverts commit 9d3a39a5f1 as that
commit causes a bunch of SELinux errors.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I73dc15c4ecddcf1950ca7fca2cc107be27da8f3f

block/ioprio.c

@@ -69,7 +69,7 @@ int ioprio_check_cap(int ioprio)
 
 	switch (class) {
 		case IOPRIO_CLASS_RT:
-			if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN))
+			if (!capable(CAP_SYS_ADMIN))
 				return -EPERM;
 			fallthrough;
 			/* rt has prio field too */

include/uapi/linux/capability.h

@@ -288,8 +288,6 @@ struct vfs_ns_cap_data {
    processes and setting the scheduling algorithm used by another
    process. */
 /* Allow setting cpu affinity on other processes */
-/* Allow setting realtime ioprio class */
-/* Allow setting ioprio class on other processes */
 
 #define CAP_SYS_NICE         23