fix(cpus): workaround for Cortex-A78C erratum 2779484

Cortex-A78C erratum 2779484 is a Cat B erratum that applies to
revisions r0p1 and r0p2 and is still open.

The workaround is to set the CPUACTLR3_EL1[47] bit to 1. Setting this
bit might have a small impact on power and negligible impact on
performance.

SDEN documentation:
https://developer.arm.com/documentation/SDEN2004089/latest



Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: I9a8c16a845c3ba6eb2f17a5119aa6ca09a0d27ed