Do not use DBUS_SERVICES in the systemd string substitutions

In order to allow other .bbappend file to append more files
into DBUS_SERVICES, remove the DBUS_SERVICES usage from
the SYSTEMD_SUBSTITUTIONS, since it only supports one file
in format SYSTEMD_SUBSTITUTIONS = "var:val:file".

Change-Id: Ic310f77dd09e5c9e1f61b901361585990ffdbe56
Signed-off-by: Yong Li <yong.b.li@linux.intel.com>
diff --git a/recipes-phosphor/ipmi/phosphor-ipmi-kcs_git.bb b/recipes-phosphor/ipmi/phosphor-ipmi-kcs_git.bb
index 87943ea..692b21e 100644
--- a/recipes-phosphor/ipmi/phosphor-ipmi-kcs_git.bb
+++ b/recipes-phosphor/ipmi/phosphor-ipmi-kcs_git.bb
@@ -13,7 +13,7 @@
 KCS_DEVICE ?= "ipmi-kcs3"
 
 DBUS_SERVICE_${PN} = "org.openbmc.HostIpmi.service"
-SYSTEMD_SUBSTITUTIONS += "KCS_DEVICE:${KCS_DEVICE}:${DBUS_SERVICE_${PN}}"
+SYSTEMD_SUBSTITUTIONS += "KCS_DEVICE:${KCS_DEVICE}:org.openbmc.HostIpmi.service"
 
 PROVIDES += "virtual/obmc-host-ipmi-hw"
 RPROVIDES_${PN} += "virtual-obmc-host-ipmi-hw"