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/chassis/obmc-phosphor-buttons_git.bb b/meta-phosphor/recipes-phosphor/chassis/obmc-phosphor-buttons_git.bb
index 933d431..f50b3d5 100644
--- a/meta-phosphor/recipes-phosphor/chassis/obmc-phosphor-buttons_git.bb
+++ b/meta-phosphor/recipes-phosphor/chassis/obmc-phosphor-buttons_git.bb
@@ -13,7 +13,7 @@
 
 BUTTON_PACKAGES="${PN}-signals ${PN}-handler"
 
-ALLOW_EMPTY_${PN} = "1"
+ALLOW_EMPTY:${PN} = "1"
 PACKAGE_BEFORE_PN += "${BUTTON_PACKAGES}"
 PACKAGECONFIG ??= "signals handler"
 SYSTEMD_PACKAGES = "${BUTTON_PACKAGES}"
@@ -21,11 +21,11 @@
 PACKAGECONFIG[signals] = ",,gpioplus nlohmann-json,"
 PACKAGECONFIG[handler] = ",,,phosphor-state-manager-chassis phosphor-state-manager-host"
 
-FILES_${PN}-signals = "${bindir}/buttons"
-SYSTEMD_SERVICE_${PN}-signals = "xyz.openbmc_project.Chassis.Buttons.service"
+FILES:${PN}-signals = "${bindir}/buttons"
+SYSTEMD_SERVICE:${PN}-signals = "xyz.openbmc_project.Chassis.Buttons.service"
 
-FILES_${PN}-handler = "${bindir}/button-handler"
-SYSTEMD_SERVICE_${PN}-handler = "phosphor-button-handler.service"
+FILES:${PN}-handler = "${bindir}/button-handler"
+SYSTEMD_SERVICE:${PN}-handler = "phosphor-button-handler.service"
 
 DEPENDS += " \
     systemd \