obmc-console cleanups

Make use of systemd class features.

Change-Id: Ia1341adc96b099d2aa43c70877d45dd32c57a500
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/common/recipes-phosphor/console/obmc-console/obmc-console-ssh@.service b/common/recipes-phosphor/console/obmc-console/obmc-console-ssh@.service
index a2e1068..198383c 100644
--- a/common/recipes-phosphor/console/obmc-console/obmc-console-ssh@.service
+++ b/common/recipes-phosphor/console/obmc-console/obmc-console-ssh@.service
@@ -5,7 +5,7 @@
 [Service]
 Environment="DROPBEAR_RSAKEY_DIR=/etc/dropbear"
 EnvironmentFile={envfiledir}/dropbear
-ExecStart=-{sbindir}/dropbear -i -r ${DROPBEAR_RSAKEY_DIR}/dropbear_rsa_host_key -c {bindir}/obmc-console-client $DROPBEAR_EXTRA_ARGS
+ExecStart=-{sbindir}/dropbear -i -r ${{DROPBEAR_RSAKEY_DIR}}/dropbear_rsa_host_key -c {bindir}/obmc-console-client $DROPBEAR_EXTRA_ARGS
 ExecReload={base_bindir}/kill -HUP $MAINPID
 StandardInput=socket
 KillMode=process