add TARGET_CPU_VARIANT to PDK ARM target

Change-Id: I6d458e49671f36cb368a784156b8ccf09074bab4
diff --git a/BoardConfig.mk b/BoardConfig.mk
index 13c2f65..5338dcb 100644
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -9,6 +9,7 @@
 
 TARGET_ARCH := arm
 TARGET_ARCH_VARIANT := armv7-a-neon
+TARGET_CPU_VARIANT := cortex-a9
 TARGET_CPU_ABI := armeabi-v7a
 TARGET_CPU_ABI2 := armeabi
 TARGET_CPU_SMP := true