fix(errata): workaround for Cortex A78C erratum 2242638

fix(errata): workaround for Cortex A78C erratum 2242638

Cortex A78C erratum 2242638 is a Cat B erratum which applies to
revisions r0p1, r0p2 and is still open. The workaround is to apply
a CPU implementation specific specific patch sequence.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN2004089/latest

Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: I35d385245a04a39b87be71c1a42312f75e1152e5