arm64: Use WFxT for __delay() when possible

mainline inclusion
from mainline-v5.19-rc1
commit 7d26b051
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6YAMV
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7d26b0516a0df5888fd1486054bc5159f6c0b88f



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Marginally optimise __delay() by using a WFIT/WFET sequence.
It probably is a win if no interrupt fires during the delay.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220419182755.601427-11-maz@kernel.org


Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>