[project][imx7d] Enable SMP for i.MX7D platform

Change-Id: I4f02eabe8642620e22a77cee91537ec1a64a4096
Signed-off-by: Haoran.Wang <elven.wang@nxp.com>
diff --git a/project/imx7d-inc.mk b/project/imx7d-inc.mk
index 301f13e..dc27783 100644
--- a/project/imx7d-inc.mk
+++ b/project/imx7d-inc.mk
@@ -18,6 +18,7 @@
 DEBUG ?= 2
 SMP_MAX_CPUS ?= 2
 SMP_CPU_CLUSTER_SHIFT ?= 1
+WITH_SMP := 1
 
 # select timer
 GLOBAL_DEFINES += TIMER_ARM_GENERIC_SELECTED=CNTPS