Fix size and sha1sum for some sdk targets

Targets such as sdk_google_phone_{x86,arm,...}-sdk
have wrong size and sha1sum in the repo-sys-img.xml,
because the sdk_repo.mk file incorrectly over-writes
the final images zip.

bug: 20927015

Change-Id: I151c8759c299d4a943f00ca2734ef65dea727262
diff --git a/build/tools/sdk_repo.mk b/build/tools/sdk_repo.mk
index db8808a..bc8481e 100644
--- a/build/tools/sdk_repo.mk
+++ b/build/tools/sdk_repo.mk
@@ -183,6 +183,7 @@
 # -----------------------------------------------------------------
 # Rules for sdk addon
 
+ifneq ($(filter sdk_addon,$(MAKECMDGOALS)),)
 ifneq ($(ADDON_SDK_ZIP),)
 
 # ADDON_SDK_ZIP is defined in build/core/tasks/sdk-addon.sh and is
@@ -224,6 +225,7 @@
 $(call dist-for-goals, sdk_repo, $(SDK_ADDON_IMG_XML))
 
 endif
+endif
 
 # -----------------------------------------------------------------
 # Rules for the SDK Repository XML