busybox: create /etc/default before using it

This fixes an error during do_install for busybox when building on dora.

recipes-core/busybox/busybox_sysmocom.inc

@@ -1,6 +1,6 @@
 SYSMOCOM := "${@os.path.dirname(bb.data.getVar('FILE', d, True))}"
 FILESEXTRAPATHS_prepend := "${SYSMOCOM}/busybox-${SYSMOCOM_ORIG_PV}:${SYSMOCOM}/files:"
-PRINC = "25"
+PRINC = "26"
 
 SRC_URI += "file://busybox-ifplugd.sh \
             file://ifplugd.sh \
@@ -28,5 +28,6 @@ do_install_append() {
 	install -m 0755 ${WORKDIR}/ifplugd.sh ${D}${sysconfdir}/
 	install -m 0755 ${WORKDIR}/busybox-ifplugd.sh ${D}${sysconfdir}/init.d/
 	install -m 0755 ${WORKDIR}/udhcpc-ntp.sh ${D}/${sysconfdir}/udhcpc.d/60ntp
+	install -d ${D}/${sysconfdir}/default
 	install -m 0644 ${WORKDIR}/udhcpc-ntp.default ${D}/${sysconfdir}/default/udhcpc-ntp
 }