genirq/affinity: Move group_cpus_evenly() into lib/

[ Upstream commit f7b3ea8c

 ]

group_cpus_evenly() has become a generic function which can be used for
other subsystems than the interrupt subsystem, so move it into lib/.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20221227022905.352674-6-ming.lei@redhat.com
Stable-dep-of: 0263f92f

 ("lib/group_cpus.c: avoid acquiring cpu hotplug lock in group_cpus_evenly")
Signed-off-by: Sasha Levin <sashal@kernel.org>