arm64: Workaround Cortex-A77 erratum 1542418 on boot due to kexec

Kexec allows us to inherit dirty ASIDs from a previous kernel. We can't
wait until the next ASID rollover to cleanup, do it early as part of
the cpu-errata's enable callback.

This extends __arm64_workaround_1542418_asid_rollover() to put everything
back as it was.

Change-Id: Ib560a10ec3c6c7d299f5874217c81ebe11cf0103
Signed-off-by: James Morse <james.morse@arm.com>
[suzuki.poulose@arm.com: skip CPUs not affected, refactor
cpu_enable callback ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Patch-mainline: linux-arm-kernel @ 11/14/19, 14:59
[sramana@codeaurora.org: Resolve trivial merge conflicts]
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>