Fix umm service skip (disable) logic

Change-Id: I033fdb224c4114b65731913076d6d2f533b61ea1
Closes-bug: #1563276

files/fuel-umm/rh7/umm_svc.local

@@ -38,5 +38,5 @@ umm-off(){
 }
 
 umm-skip(){
-    return 0
+    exit 0
 }

files/fuel-umm/root/usr/lib/umm/umm_svc

@@ -7,8 +7,8 @@ set_umm(){
     echo umm >$UMM_FLAG
 }
 
-# check if UMM enabled and sckip processing any services
-[[ "$UMM" == "yes" ]] || exit 0
+# check if UMM enabled and skip processing any services
+[[ "$UMM" == "yes" ]] || umm-skip
 
 if [[ "$1" == "timer" ]] ; then
     sleep $(($COUNTER_RESET_TIME*60))

files/fuel-umm/ub14/umm_svc.local

@@ -13,5 +13,5 @@ umm-off(){
 
 umm-skip(){
     /sbin/initctl emit umm
-    return 0
+    exit 0
 }