SPMD: enable SPM dispatcher support

This patch adds support to the build system to include support for the SPM
dispatcher when the SPD configuration option is spmd.

Signed-off-by: Achin Gupta <achin.gupta@arm.com>
Signed-off-by: Artsem Artsemenka <artsem.artsemenka@arm.com>
Change-Id: Ic1ae50ecd7403fcbcf1d318abdbd6ebdc642f732
diff --git a/bl31/bl31.mk b/bl31/bl31.mk
index 58909e8..0948e94 100644
--- a/bl31/bl31.mk
+++ b/bl31/bl31.mk
@@ -31,6 +31,7 @@
 				services/arm_arch_svc/arm_arch_svc_setup.c	\
 				services/std_svc/std_svc_setup.c		\
 				${PSCI_LIB_SOURCES}				\
+				${SPMD_SOURCES}					\
 				${SPM_SOURCES}