Revert "clk: Get runtime PM before walking tree during disable_unused"

This reverts commit 253ab38d which is
commit e581cf5d216289ef292d1a4036d53ce90e122469 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: Ic3614277b0ce1e1eec3488d1f3db21cc538aa3d4
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>