fix(cpus): workaround for Cortex-A76 erratum 2743102

Cortex-A76 erratum 2743102 is a Cat B erratum that applies to
all revisions <=r4p1 and is still open. The workaround is to
insert a dsb before the isb in the power down sequence.

SDEN documentation:
https://developer.arm.com/documentation/SDEN885749/latest

Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
Change-Id: Ie2cd73bd91417d30b5633d80b2fbee32944bc2de
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 37120c9..03b3ee5 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -256,6 +256,10 @@
 -  ``ERRATA_A76_1946160``: This applies errata 1946160 workaround to Cortex-A76
    CPU. This needs to be enabled only for revisions r3p0 - r4p1 of the CPU.
 
+-  ``ERRATA_A76_2743102``: This applies errata 2743102 workaround to Cortex-A76
+   CPU. This needs to be enabled for all revisions <= r4p1 of the CPU and is
+   still open.
+
 For Cortex-A77, the following errata build flags are defined :
 
 -  ``ERRATA_A77_1508412``: This applies errata 1508412 workaround to Cortex-A77