Workaround for Cortex A76 erratum 1868343

Cortex A76 erratum 1868343 is a Cat B erratum, present in older
revisions of the Cortex A76 processor core.  The workaround is to
set a bit in the CPUACTLR_EL1 system register, which delays instruction
fetch after branch misprediction. This workaround will have a small
impact on performance.

This workaround is the same as workarounds for errata 1262606 and
1275112, so all 3 have been combined into one function call.

SDEN can be found here:
https://documentation-service.arm.com/static/5f2bed6d60a93e65927bc8e7

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I7f2f9965f495540a1f84bb7dcc28aff45d6cee5d
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 5df94cc..925ed5f 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -278,6 +278,10 @@
 # to all revisions of Cortex A76 cpu.
 ERRATA_A76_1165522	?=0
 
+# Flag to apply erratum 1868343 workaround during reset. This erratum applies
+# only to revision <= r4p0 of the Cortex A76 cpu.
+ERRATA_A76_1868343	?=0
+
 # Flag to apply erratum 1508412 workaround during reset. This erratum applies
 # only to revision <= r1p0 of the Cortex A77 cpu.
 ERRATA_A77_1508412	?=0
@@ -555,6 +559,10 @@
 $(eval $(call assert_boolean,ERRATA_A76_1165522))
 $(eval $(call add_define,ERRATA_A76_1165522))
 
+# Process ERRATA_A76_1868343 flag
+$(eval $(call assert_boolean,ERRATA_A76_1868343))
+$(eval $(call add_define,ERRATA_A76_1868343))
+
 # Process ERRATA_A77_1508412 flag
 $(eval $(call assert_boolean,ERRATA_A77_1508412))
 $(eval $(call add_define,ERRATA_A77_1508412))