percpu_ref: reorganize __percpu_ref_switch_to_atomic() and relocate percpu_ref_switch...

percpu_ref: reorganize __percpu_ref_switch_to_atomic() and relocate percpu_ref_switch_to_atomic()

Reorganize __percpu_ref_switch_to_atomic() so that it looks
structurally similar to __percpu_ref_switch_to_percpu() and relocate
percpu_ref_switch_to_atomic so that the two internal functions are
co-located.

This patch doesn't introduce any functional differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
(cherry picked from commit b2302c7fdc654d249c546aac6228b8e10969bc1e)

Orabug: 26254388

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Ashok Vairavan <ashok.vairavan@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>