errata: workaround for Cortex-A78 erratum 2132060

Cortex-A78 erratum 2132060 is a Cat B erratum that applies to
revisions r0p0, r1p0, r1p1, and r1p2 of CPU. It is still open.
The workaround is to write the value 2'b11 to the PF_MODE bits
in the CPUECTLR_EL1 register which will place the data prefetcher
in the most conservative mode instead of disabling it.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1401784/latest

Signed-off-by: nayanpatel-arm <nayankumar.patel@arm.com>
Change-Id: If7dec72578633d37d110d103099e406c3a970ff7
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 944228c..3955a05 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -284,6 +284,10 @@
 -  ``ERRATA_A78_1952683``: This applies errata 1952683 workaround to Cortex-A78
    CPU. This needs to be enabled for revision r0p0, it is fixed in r1p0.
 
+-  ``ERRATA_A78_2132060``: This applies errata 2132060 workaround to Cortex-A78
+   CPU. This needs to be enabled for revisions r0p0, r1p0, r1p1, and r1p2. It
+   is still open.
+
 For Cortex-A78 AE, the following errata build flags are defined :
 
 - ``ERRATA_A78_AE_1941500`` : This applies errata 1941500 workaround to Cortex-A78