mainline inclusion
from mainline-v5.12-rc1
commit 8ecca394
category: feature
feature: SPR PMU uncore support
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I5BECO

Intel-SIG: commit 8ecca394 rbtree, sched/deadline: Use
rb_add_cached()
This commit is backported as a dependency for SPR PMU uncore support.

-------------------------------------

Reduce rbtree boiler plate by using the new helpers.

Make rb_add_cached() / rb_erase_cached() return a pointer to the
leftmost node to aid in updating additional state.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Acked-by: NDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: NYunying Sun <yunying.sun@intel.com>