fix(errata): workaround for Neoverse-N2 erratum 2242400

Neoverse-N2 erratum 2242400 is a Cat B erratum that applies to
revision r0p0 of CPU. It is still open. The workaround
is to set CPUACTLR5_EL1[17] to 1'b1 followed by setting few
system control registers to specific values as per attached
SDEN document.

SDEN can be found here:
https://developer.arm.com/documentation/SDEN1982442/latest

Signed-off-by: nayanpatel-arm <nayankumar.patel@arm.com>
Change-Id: I6a9cb4a23238b8b511802a1ee9fcc5b207137649
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index b676987..f0da139 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -469,6 +469,10 @@
 # to revision r0p0 of the Neoverse N2 cpu and is still open.
 ERRATA_N2_2138958	?=0
 
+# Flag to apply erratum 2242400 workaround during reset. This erratum applies
+# to revision r0p0 of the Neoverse N2 cpu and is still open.
+ERRATA_N2_2242400	?=0
+
 # Flag to apply erratum 2055002 workaround during reset. This erratum applies
 # to revision r1p0, r2p0 of the Cortex-A710 cpu and is still open.
 ERRATA_A710_2055002	?=0
@@ -878,6 +882,10 @@
 $(eval $(call assert_boolean,ERRATA_N2_2138958))
 $(eval $(call add_define,ERRATA_N2_2138958))
 
+# Process ERRATA_N2_2242400 flag
+$(eval $(call assert_boolean,ERRATA_N2_2242400))
+$(eval $(call add_define,ERRATA_N2_2242400))
+
 # Process ERRATA_A710_2055002 flag
 $(eval $(call assert_boolean,ERRATA_A710_2055002))
 $(eval $(call add_define,ERRATA_A710_2055002))