fix(cpus): workaround for Cortex-A78C erratum 2376749

Cortex-A78C erratum 2376749 is a Cat B erratum that applies
to revisions r0p1 and r0p2 of the A78C and is currently open.
The workaround is to set CPUACTLR2_EL1[0] to 1 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/SDEN2004089/latest



Signed-off-by: Akram Ahmad <Akram.Ahmad@arm.com>
Change-Id: I3b29f4b7f167bf499d5d11ffef91a94861bd1383