fix(cpus): workaround for Cortex-A720 erratum 2844092

Cortex-A720 erratum 2844092 is a Cat B erratum that is present
in revisions r0p0, r0p1 and is fixed in r0p2.

The workaround is to set bit[11] of CPUACTLR4_EL1 register.

SDEN documentation:
https://developer.arm.com/documentation/SDEN-2439421/latest



Change-Id: I3d8eacb26cba42774f1f31c3aae2a0e6fecec614
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>