fix(cpus): workaround for Cortex-A710 erratum 1917258

Cortex-A710 erratum 1917258 is a Cat B erratum that applies
to revisions r0p0 and r1p0 and is fixed in r2p0.

The workaround is to set CPUACTLR4_EL1[43]. This has no
performance impact.

SDEN documentation:
https://developer.arm.com/documentation/SDEN1775101

Change-Id: I1fae91a5e3a8ecea255f0f0a481bfd6196a7db51
Signed-off-by: John Powell <john.powell@arm.com>
3 files changed