fix(errata): workaround for Neoverse-N2 erratum 2376738

Neoverse-N2 erratum 2376738 is a Cat B erratum that applies
to revision r0p0 of the CPU. It is fixed in r0p1. The workaround
is to set CPUACTLR2_EL1[0] to 1 to force PLDW/PFRM ST to
behave like PLD/PRFM LD and not cause invalidations to other
PE caches.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1982442/latest



Signed-off-by: Akram Ahmad <Akram.Ahmad@arm.com>
Change-Id: I4ad4434f9b7210244e67046d9657d218857dced5