fix(errata): workaround for Cortex X2 erratum 2002765

Cortex X2 erratum 2002765 is a Cat B erratum present in the X2 core.
It applies to revisions r0p0, r1p0, and r2p0 and is still open.

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



Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I11576a03bfd8a6b1bd9ffef4430a097d763ca3cf