Cortex-A15: Implement workaround for errata 827671

This erratum can only be worked around on revisions >= r3p0 because the
register that needs to be accessed only exists in those revisions[1].

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0438g/CIHEAAAD.html

Change-Id: I5d773547d7a09b5bd01dabcd19ceeaf53c186faa
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>
diff --git a/docs/cpu-specific-build-macros.rst b/docs/cpu-specific-build-macros.rst
index a9ed9c1..8c951de 100644
--- a/docs/cpu-specific-build-macros.rst
+++ b/docs/cpu-specific-build-macros.rst
@@ -76,6 +76,9 @@
 -  ``ERRATA_A15_816470``: This applies errata 816470 workaround to Cortex-A15
    CPU. This needs to be enabled only for revision >= r3p0 of the CPU.
 
+-  ``ERRATA_A15_827671``: This applies errata 827671 workaround to Cortex-A15
+   CPU. This needs to be enabled only for revision >= r3p0 of the CPU.
+
 For Cortex-A53, the following errata build flags are defined :
 
 -  ``ERRATA_A53_819472``: This applies errata 819472 workaround to all