Add workaround for errata 764081 of Cortex-A75

Implicit Error Synchronization Barrier (IESB) might not be correctly
generated in Cortex-A75 r0p0. To prevent this, IESB are enabled at all
expection levels.

Change-Id: I2a1a568668a31e4f3f38d0fba1d632ad9939e5ad
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index a9c6fda..be7d3bd 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -123,6 +123,10 @@
 # only to revision <= r0p1 of the Cortex A73 cpu.
 ERRATA_A73_855423	?=0
 
+# Flag to apply erratum 764081 workaround during reset. This erratum applies
+# only to revision <= r0p0 of the Cortex A75 cpu.
+ERRATA_A75_764081	?=0
+
 # Flag to apply T32 CLREX workaround during reset. This erratum applies
 # only to r0p0 and r1p0 of the Neoverse N1 cpu.
 ERRATA_N1_1043202	?=1
@@ -196,6 +200,10 @@
 $(eval $(call assert_boolean,ERRATA_A73_855423))
 $(eval $(call add_define,ERRATA_A73_855423))
 
+# Process ERRATA_A75_764081 flag
+$(eval $(call assert_boolean,ERRATA_A75_764081))
+$(eval $(call add_define,ERRATA_A75_764081))
+
 # Process ERRATA_N1_1043202 flag
 $(eval $(call assert_boolean,ERRATA_N1_1043202))
 $(eval $(call add_define,ERRATA_N1_1043202))