fix(errata): workaround for Cortex-A77 erratum 2356587

Cortex-A77 erratum 2356587 is a cat B erratum that applies to revisions
r0p0 - r1p1 and is still open. The workaround is to set bit[0] of
CPUACTLR2_EL1 to 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/SDEN1152370/latest



Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: I243cfd587bca06ffd2a7be5bce28f8d2c5e68230