feat: add build flag to control support for CPU_OFF psci msg

Please check the inline comments for detailed description of the
new build flag. This flag will help us to create a negative test
scenario where we can exercise sending DENIED response to SPMC,
ultimately leading to a panic by SPMD.

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: I30d2ea7f3fbf09e4e4febceb85f045e25f3e6035
diff --git a/Makefile b/Makefile
index 4936ff7..29b0f3b 100644
--- a/Makefile
+++ b/Makefile
@@ -171,6 +171,7 @@
 $(eval $(call assert_boolean,ENABLE_REALM_PAYLOAD_TESTS))
 $(eval $(call assert_boolean,TRANSFER_LIST))
 $(eval $(call assert_boolean,SPMC_AT_EL3))
+$(eval $(call assert_boolean,CACTUS_PWR_MGMT_SUPPORT))
 
 ################################################################################
 # Process build options
@@ -199,6 +200,7 @@
 $(eval $(call add_define,TFTF_DEFINES,TRANSFER_LIST))
 $(eval $(call add_define,TFTF_DEFINES,PLAT_AMU_GROUP1_COUNTERS_MASK))
 $(eval $(call add_define,TFTF_DEFINES,SPMC_AT_EL3))
+$(eval $(call add_define,TFTF_DEFINES,CACTUS_PWR_MGMT_SUPPORT))
 
 ################################################################################