arm64: errata: Add workaround for TSB flush failures

Arm Neoverse-N2 (#2067961) and Cortex-A710 (#2054223) suffers
from errata, where a TSB (trace synchronization barrier)
fails to flush the trace data completely, when executed from
a trace prohibited region. In Linux we always execute it
after we have moved the PE to trace prohibited region. So,
we can apply the workaround every time a TSB is executed.

The work around is to issue two TSB consecutively.

NOTE: This errata is defined as LOCAL_CPU_ERRATUM, implying
that a late CPU could be blocked from booting if it is the
first CPU that requires the workaround. This is because we
do not allow setting a cpu_hwcaps after the SMP boot. The
other alternative is to use "this_cpu_has_cap()" instead
of the faster system wide check, which may be a bit of an
overhead, given we may have to do this in nvhe KVM host
before a guest entry.

Cc: Will Deacon <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Mike Leach <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Marc Zyngier <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Reviewed-by: Mathieu Poirier <[email protected]>
Reviewed-by: Anshuman Khandual <[email protected]>
Signed-off-by: Suzuki K Poulose <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

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