meta-openpower: phosphor: move all services to multi-user.target

Instead of obmc-standby.target, use multi-user.target.

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I8a0c91b224ef4054e902fc06855ae12f083cbda5
diff --git a/recipes-phosphor/occ/openpower-occ-control/org.open_power.OCC.Control.service b/recipes-phosphor/occ/openpower-occ-control/org.open_power.OCC.Control.service
index a63e186..d16bcdc 100644
--- a/recipes-phosphor/occ/openpower-occ-control/org.open_power.OCC.Control.service
+++ b/recipes-phosphor/occ/openpower-occ-control/org.open_power.OCC.Control.service
@@ -11,4 +11,4 @@
 BusName={BUSNAME}
 
 [Install]
-WantedBy={SYSTEMD_DEFAULT_TARGET}
+WantedBy=multi-user.target