Rename USER_OBJS to user-obj-y

Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/Makefile b/Makefile
index 5bedffd..dfb55cf 100644
--- a/Makefile
+++ b/Makefile
@@ -236,10 +236,10 @@
 libqemu_common.a: $(OBJS)
 
 #######################################################################
-# USER_OBJS is code used by qemu userspace emulation
-USER_OBJS=cutils.o  cache-utils.o
+# user-obj-y is code used by qemu userspace emulation
+user-obj-y = cutils.o cache-utils.o
 
-libqemu_user.a: $(USER_OBJS)
+libqemu_user.a: $(user-obj-y)
 
 ######################################################################