fix(errata): workaround for Cortex-A510 erratum 2041909

Cortex-A510 erratum 2041909 is a Cat B erratum that applies to revision
r0p2 and is fixed in r0p3. It is also present in r0p0 and r0p1 but there
is no workaround in these revisions.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN2397239



Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I7b1498faa0c79488dee0d11d07f6e9f58144e298