Use armv7-a when building sdk.

Bug: http://b/68201917
Test: make sdk.
Change-Id: I7817bc03beb109b4152d3bc751f0d2438cc93e3b
diff --git a/target/board/generic_arm64/BoardConfig.mk b/target/board/generic_arm64/BoardConfig.mk
index d6df2cf..9beb9a3 100644
--- a/target/board/generic_arm64/BoardConfig.mk
+++ b/target/board/generic_arm64/BoardConfig.mk
@@ -25,7 +25,7 @@
 TARGET_2ND_CPU_ABI := armeabi-v7a
 TARGET_2ND_CPU_ABI2 := armeabi
 
-ifneq ($(TARGET_BUILD_APPS)$(filter cts,$(MAKECMDGOALS)),)
+ifneq ($(TARGET_BUILD_APPS)$(filter cts sdk,$(MAKECMDGOALS)),)
 # DO NOT USE
 # DO NOT USE
 #