feat(spmd): introduce platform handler for Group0 interrupt

This patch introduces a handler for FVP platform to triage Group0
secure interrupts. Currently, it is empty but serves as a
placeholder for future Group0 interrupt sources.

Moreover, this patch also provides a dummy implementation of the
above mentioned platform hook for QEMU, corstone100, n1sdp and
hikey960 ports.

Change-Id: I01d3451408f47ac313b0af74046cce89f89b85bb
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
diff --git a/plat/arm/board/fvp/fvp_spmd.c b/plat/arm/board/fvp/fvp_spmd.c
new file mode 100644
index 0000000..8213e5e
--- /dev/null
+++ b/plat/arm/board/fvp/fvp_spmd.c
@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2023, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdint.h>
+
+int plat_spmd_handle_group0_interrupt(uint32_t intid)
+{
+	/*
+	 * As of now, there are no sources of Group0 secure interrupt enabled
+	 * for FVP.
+	 */
+	(void)intid;
+	return -1;
+}