ensure volatile clear waits on dependency

The "Wants" relationship is required to ensure the mapper wait service
is properly started and waited on.

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: If7a880ec0586bc5fbde1e164b415fb28abb8d8ff
diff --git a/ubi/obmc-flash-bios-enable-clearvolatile@.service b/ubi/obmc-flash-bios-enable-clearvolatile@.service
index 6fe05c7..10537d7 100644
--- a/ubi/obmc-flash-bios-enable-clearvolatile@.service
+++ b/ubi/obmc-flash-bios-enable-clearvolatile@.service
@@ -1,5 +1,6 @@
 [Unit]
 Description=Enable the clearing of the Volatile PNOR partitions in host%I
+Wants=mapper-wait@-org-open_power-control-volatile.service
 After=mapper-wait@-org-open_power-control-volatile.service
 Before=obmc-flash-bios-check-clearvolatile@%i.service
 ConditionPathExists=!/run/openbmc/host@%i-on