dropbear: move systemd support to meta-systemd

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>

meta-systemd/meta-oe/recipes-core/dropbear/dropbear_2012.55.bbappend

@@ -1,9 +1,9 @@
 inherit systemd
 
-PRINC := "${@int(PRINC) + 2}"
+PRINC := "${@int(PRINC) + 3}"
 
 # look for files in the layer first
-FILESEXTRAPATHS := "${THISDIR}/${PN}"
+FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
 
 SRC_URI += "file://dropbearkey.service \
             file://dropbear@.service \