fix(errata): workaround for Cortex-A710 2282622

Cortex-A710 erratum 2282622 is a Cat B erratum that applies to revisions
r0p0, r1p0, and r2p0, and is fixed in r2p1. The workaround is to set
CPUACTLR2_EL1[0] to 1, which will force PLDW/PFRM ST to behave like
PLD/PRFM LD and not cause invalidations to other PE caches.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1775101



Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: Ic48409822536e9eacc003300036a1f0489593020