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/platform.mk b/plat/arm/board/fvp/platform.mk
index af082ba..64d5c3f 100644
--- a/plat/arm/board/fvp/platform.mk
+++ b/plat/arm/board/fvp/platform.mk
@@ -510,3 +510,7 @@
     endif
 BL31_SOURCES	+= plat/arm/board/fvp/aarch64/fvp_ea.c
 endif
+
+ifeq (${SPD},spmd)
+BL31_SOURCES	+=	plat/arm/board/fvp/fvp_spmd.c
+endif