meta-ibm: prep for new override syntax

Change-Id: I9116ed7260e369136acb39eec15075db2d4dbeba
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/meta-ibm/recipes-phosphor/dbus/phosphor-mapper-config-native.bbappend b/meta-ibm/recipes-phosphor/dbus/phosphor-mapper-config-native.bbappend
index d94a554..25ab376 100644
--- a/meta-ibm/recipes-phosphor/dbus/phosphor-mapper-config-native.bbappend
+++ b/meta-ibm/recipes-phosphor/dbus/phosphor-mapper-config-native.bbappend
@@ -1 +1 @@
-PHOSPHOR_MAPPER_CONFIGS_append = " ibm-dbus-interfaces-mapper-config-native"
+PHOSPHOR_MAPPER_CONFIGS:append = " ibm-dbus-interfaces-mapper-config-native"