Register ALL_MODULES subvars with my_register_name

Replace ALL_MODULES.$(LOCAL_MODULE) with
ALL_MODULES.$(my_register_name).

Test: TH presubmit build pass
Change-Id: Ic1fb859ae458d1c67cc1d3699199ef36476088db
diff --git a/apex/androidmk.go b/apex/androidmk.go
index db1048e..2c5407c 100644
--- a/apex/androidmk.go
+++ b/apex/androidmk.go
@@ -308,7 +308,7 @@
 				fmt.Fprintln(w, "include $(BUILD_PREBUILT)")
 
 				if apexType == imageApex {
-					fmt.Fprintln(w, "ALL_MODULES.$(LOCAL_MODULE).BUNDLE :=", a.bundleModuleFile.String())
+					fmt.Fprintln(w, "ALL_MODULES.$(my_register_name).BUNDLE :=", a.bundleModuleFile.String())
 				}
 
 				if a.installedFilesFile != nil {