fix(cpus): workaround for Cortex-A78C erratum 2683027

Cortex-A78C erratum 2683027 is a cat B erratum that applies to
revisions r0p1 - r0p2 and is still open. The workaround is to
execute a specific code sequence in EL3 during reset.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN-2004089/latest

Change-Id: I2bf9e675f48b62b4cd203100f7df40f4846aafa8
Signed-off-by: Bipin Ravi <bipin.ravi@arm.com>
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 287d32b..3485dc9 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -384,6 +384,10 @@
   Cortex-A78C CPU. This needs to be enabled for revisions r0p1 and r0p2. This
   erratum is still open.
 
+- ``ERRATA_A78C_2683027`` : This applies errata 2683027 workaround to
+  Cortex-A78C CPU. This needs to be enabled for revisions r0p1 and r0p2. This
+  erratum is still open.
+
 - ``ERRATA_A78C_2712575`` : This applies erratum 2712575 workaround to
   Cortex-A78C CPU, this erratum affects system configurations that do not use
   an ARM interconnect IP. This needs to be enabled for revisions r0p1 and r0p2