Revert "Simplify arch target handling"

This reverts commit 6713fb26cbcadf525cd75e47d7d0cbc23d282b3e.

Change-Id: Ic473cea2563b0b37dc08b0bc5d3a0ac8c4b6afe6
diff --git a/cc/arm64_device.go b/cc/arm64_device.go
index 8e7c57b..4e41287 100644
--- a/cc/arm64_device.go
+++ b/cc/arm64_device.go
@@ -208,5 +208,5 @@
 }
 
 func init() {
-	registerToolchainFactory(android.Android, android.Arm64, arm64ToolchainFactory)
+	registerDeviceToolchainFactory(android.Arm64, arm64ToolchainFactory)
 }