fvp: use two instances of Cactus at S-EL1

To demonstrate communication between SP's two instances of Cactus at
S-EL1 has been used.
This patch replaces Ivy SP with cactus-secondary SP which aligns with
changes in tf-a-tests repository.
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: Iee84f1f7f023b7c4f23fbc13682a42614a7f3707

plat/arm/board/fvp/fdts/fvp_fw_config.dts

@@ -102,12 +102,12 @@
 
 	secure-partitions {
 		compatible = "arm,sp";
-		cactus {
+		cactus-primary {
 			uuid = <0x1e67b5b4 0xe14f904a 0x13fb1fb8 0xcbdae1da>;
 			load-address = <0x7000000>;
 		};
 
-		ivy {
+		cactus-secondary {
 			uuid = <0x092358d1 0xb94723f0 0x64447c82 0xc88f57f5>;
 			load-address = <0x7100000>;
 		};