fix(cpus): workaround for Cortex-A520 erratum 2858100

Cortex-A520 erratum 2858100 is a Cat B erratum that applies to
all revisions <=r0p1 and is still open. The workaround is to
set bit[29] of CPUACTLR_EL1.

SDEN Documentation:
https://developer.arm.com/documentation/SDEN-2444153/latest

Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
Change-Id: I5a07163f919352583b03328abd5659bf7b268677
5 files changed