tools include UAPI: Sync linux/sched.h copy with the kernel sources

Picking the changes from:

  f0e1a064 ("sched_ext: Implement BPF extensible scheduler class")

The inclusion of the SCHED_EXT define doesn't cause any change in
behaviour in tools/perf.

This just silences this perf tools build warning:

  diff -u tools/perf/trace/beauty/include/uapi/sound/asound.h include/uapi/sound/asound.h

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/lkml/ZvrDShNVXotZpiwk@x1Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/trace/beauty/include/uapi/linux/sched.h

@@ -118,6 +118,7 @@ struct clone_args {
 /* SCHED_ISO: reserved but not implemented yet */
 #define SCHED_IDLE		5
 #define SCHED_DEADLINE		6
+#define SCHED_EXT		7
 
 /* Can be ORed in to make sure the process is reverted back to SCHED_NORMAL on fork */
 #define SCHED_RESET_ON_FORK     0x40000000