feat(rmm) : add api for rec force exit

add api to force exit a rec
added testcase for force exit rec

Signed-off-by: Shruti Gupta <shruti.gupta@arm.com>
Change-Id: I56c70234e236c7d3615237d11c773bdb970012e3
diff --git a/realm/realm_payload_main.c b/realm/realm_payload_main.c
index 2271221..1440716 100644
--- a/realm/realm_payload_main.c
+++ b/realm/realm_payload_main.c
@@ -33,6 +33,13 @@
 	waitms(sleep);
 }
 
+static void realm_loop_cmd(void)
+{
+	while (true) {
+		waitms(500);
+	}
+}
+
 /*
  * This function requests RSI/ABI version from RMM.
  */
@@ -74,6 +81,10 @@
 			realm_sleep_cmd();
 			test_succeed = true;
 			break;
+		case REALM_LOOP_CMD:
+			realm_loop_cmd();
+			test_succeed = true;
+			break;
 		case REALM_MULTIPLE_REC_PSCI_DENIED_CMD:
 			test_succeed = test_realm_multiple_rec_psci_denied_cmd();
 			break;