fix(cpus): workaround for Cortex-A78 erratum 2779479

fix(cpus): workaround for Cortex-A78 erratum 2779479

Cortex-A78 erratum 2779479 is a Cat B erratum that applies to
all revisions <= r1p2 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/SDEN1401784/latest

Change-Id: I3779fd1eff3017c5961ffa101b357918070b3b36
Signed-off-by: Sona Mathew <SonaRebecca.Mathew@arm.com>