classes-dbus: General refactoring

Take the more idiomatic approach of iterating on
DBUS_PACKAGES to find files.

Change-Id: I7656316b839f666bd1b25b757bef2c14a2cee326
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/common/recipes-phosphor/obmc-phosphor-example-sdbus/obmc-phosphor-example-sdbus.bb b/common/recipes-phosphor/obmc-phosphor-example-sdbus/obmc-phosphor-example-sdbus.bb
index 9a3018d..541aa79 100644
--- a/common/recipes-phosphor/obmc-phosphor-example-sdbus/obmc-phosphor-example-sdbus.bb
+++ b/common/recipes-phosphor/obmc-phosphor-example-sdbus/obmc-phosphor-example-sdbus.bb
@@ -2,9 +2,7 @@
 DESCRIPTION = "Phosphor OpenBMC QEMU BSP example implementation."
 PR = "r1"
 
-DBUS_SERVICES = " \
-        org.openbmc.examples.SDBusService \
-        "
+DBUS_SERVICE_${PN} += "org.openbmc.examples.SDBusService"
 
 S = "${WORKDIR}"
 SRC_URI += "file://Makefile \