Add cortex-a53 cpu variant

Used in bionic

Change-Id: I5936f8468937fc259ef75d8278a592b8a7b07077
diff --git a/common/arch.go b/common/arch.go
index b9e3a5c..22393cc 100644
--- a/common/arch.go
+++ b/common/arch.go
@@ -130,7 +130,8 @@
 		Denver     interface{} `blueprint:"filter(android:\"arch_variant\")"`
 
 		// Arm64 cpu variants
-		Denver64 interface{} `blueprint:"filter(android:\"arch_variant\")"`
+		Cortex_a53 interface{} `blueprint:"filter(android:\"arch_variant\")"`
+		Denver64   interface{} `blueprint:"filter(android:\"arch_variant\")"`
 
 		// Mips arch variants
 		Mips_rev6 interface{} `blueprint:"filter(android:\"arch_variant\")"`