fix(errata): workaround for Cortex A78 AE erratum 2395408

Cortex A78 AE erratum 2395408 is a Cat B erratum that applies
to revisions <= r0p1. It is still open.

This erratum states, "A translation table walk that matches an
existing L1 prefetch with a read request outstanding on CHI might
fold into the prefetch, which might lead to data corruption for
a future instruction fetch"

This erratum is avoided by setting CPUACTLR2_EL1[40] to 1 to
disable folding of demand requests into older prefetches with
L2 miss requests outstanding.

SDEN is available at https://developer.arm.com/documentation/SDEN-1707912

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Change-Id: Ic17968987ca3c67fa7f64211bcde6dfcb35ed5d6
diff --git a/include/lib/cpus/aarch64/cortex_a78.h b/include/lib/cpus/aarch64/cortex_a78.h
index 06c27ad..31da99e 100644
--- a/include/lib/cpus/aarch64/cortex_a78.h
+++ b/include/lib/cpus/aarch64/cortex_a78.h
@@ -38,6 +38,7 @@
 #define CORTEX_A78_ACTLR2_EL1_BIT_0			(ULL(1) << 0)
 #define CORTEX_A78_ACTLR2_EL1_BIT_1			(ULL(1) << 1)
 #define CORTEX_A78_ACTLR2_EL1_BIT_2			(ULL(1) << 2)
+#define CORTEX_A78_ACTLR2_EL1_BIT_40			(ULL(1) << 40)
 
 /*******************************************************************************
  * CPU Activity Monitor Unit register specific definitions.