sched/rt: Fix Sparse warnings due to undefined rt.c declarations

sched/rt: Fix Sparse warnings due to undefined rt.c declarations

There are several symbols defined in kernel/sched/sched.h but get wrapped
in CONFIG_CGROUP_SCHED, even though dummy versions get built in rt.c and
therefore trigger Sparse warnings:

  kernel/sched/rt.c:309:6: warning: symbol 'unregister_rt_sched_group' was not declared. Should it be static?
  kernel/sched/rt.c:311:6: warning: symbol 'free_rt_sched_group' was not declared. Should it be static?
  kernel/sched/rt.c:313:5: warning: symbol 'alloc_rt_sched_group' was not declared. Should it be static?

Fix this by moving them outside the CONFIG_CGROUP_SCHED block.

[ mingo: Refreshed to the latest scheduler tree, tweaked changelog. ]

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20220721145155.358366-1-ben-linux@fluff.org