meta-phosphor: prep for new override syntax

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I588025b614416c43aa2d053765ab53bacf890cb5
diff --git a/meta-phosphor/recipes-phosphor/interfaces/slpd-lite_git.bb b/meta-phosphor/recipes-phosphor/interfaces/slpd-lite_git.bb
index 0022d92..6eaed0f 100644
--- a/meta-phosphor/recipes-phosphor/interfaces/slpd-lite_git.bb
+++ b/meta-phosphor/recipes-phosphor/interfaces/slpd-lite_git.bb
@@ -9,7 +9,7 @@
 inherit autotools pkgconfig
 inherit obmc-phosphor-systemd
 
-SYSTEMD_SERVICE_${PN} += "slpd-lite.service"
+SYSTEMD_SERVICE:${PN} += "slpd-lite.service"
 
 DEPENDS += "systemd"
 DEPENDS += "autoconf-archive-native"