fix(cpus): workaround for Cortex-X3 erratum 2070301

Cortex-X3 erratum 2070301 is a Cat B erratum that applies to all
revisions <= r1p2 and is still open.
The workaround is to write the value 4'b1001 to the PF_MODE bits
in the IMP_CPUECTLR2_EL1 register. This places the data prefetcher
in the most conservative mode instead of disabling it.

SDEN documentation:
https://developer.arm.com/documentation/2055130/latest

Change-Id: I337c4c7bb9221715aaf973a55d0154e1c7555768
Signed-off-by: Sona Mathew <sonarebecca.mathew@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 77cc41e..e12795f 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -734,6 +734,11 @@
 # still open.
 CPU_FLAG_LIST += ERRATA_X2_2768515
 
+# Flag to apply erratum 2070301 workaround on reset. This erratum applies
+# to revisions r0p0, r1p0, r1p1 and r1p2 of the Cortex-X3 cpu and is
+# still open.
+CPU_FLAG_LIST += ERRATA_X3_2070301
+
 # Flag to apply erratum 2313909 workaround on powerdown. This erratum applies
 # to revisions r0p0 and r1p0 of the Cortex-X3 cpu, it is fixed in r1p1.
 CPU_FLAG_LIST += ERRATA_X3_2313909