fix(errata): workaround for Cortex-X2 erratum 2216384

Cortex-X2 erratum 2216384 is a Cat B erratum that applies to
revisions r0p0, r1p0 and r2p0 of CPU. It is fixed in r2p1.
The workaround is to set CPUACTLR5_EL1[17] to 1'b1 followed by
applying an instruction patching sequence.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1775100/latest



Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: I3c216161678887c06a28c59644e784e0c7d37bab