fix(errata): workaround for Neoverse-V1 erratum 2294912

Neoverse-V1 erratum 2294912 is a cat B erratum that applies to revisions
r0p0 - r1p1 and is still open. The workaround is to set bit[0] of
CPUACTLR2_EL1 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/SDEN1401781/latest

Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: Ia7afb4c42fe66b36fdf38a7d4281a0d168f68354
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index fbd2cbc..01bd496 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -414,6 +414,10 @@
    issue is present in r0p0 as well but there is no workaround for that
    revision.  It is still open.
 
+-  ``ERRATA_V1_2294912``: This applies errata 2294912 workaround to Neoverse-V1
+   CPU. This needs to be enabled for revisions r0p0, r1p0, and r1p1 of the CPU.
+   It is still open.
+
 For Cortex-A710, the following errata build flags are defined :
 
 -  ``ERRATA_A710_1987031``: This applies errata 1987031 workaround to