systemd: remove hwdb

This change completely removes hwdb and all associated files from the
image. The BMC isn't using any of the devices in the database.

Resvoles #219

Change-Id: I07e028c6a75cd78c0812c50633768042d3136adb
Signed-off-by: Edward A. James <eajames@us.ibm.com>

meta-phosphor/common/recipes-core/systemd/systemd_%.bbappend

@@ -7,6 +7,8 @@ SRC_URI += "file://obmc-standby.target"
 FILES_${PN} += "${libdir}/systemd/network/default.network"
 FILES_${PN} += "${systemd_system_unitdir}/obmc-standby.target"
 
+EXTRA_OECONF += " --disable-hwdb"
+
 do_install_append() {
         install -m 644 ${WORKDIR}/default.network ${D}${libdir}/systemd/network/
         install -m 644 ${WORKDIR}/obmc-standby.target ${D}${systemd_system_unitdir}