libosmo-abis.inc: Use PACKAGECONFIG to handle dahdi support, enable it by default

Building with DAHDI support can be controlled by bbappend or config file
on the BSP meta layer as described here:
https://www.yoctoproject.org/docs/current/ref-manual/ref-manual.html#var-PACKAGECONFIG

Change-Id: I0d875896bc97e973489672f004cb49fae02bdd46
diff --git a/recipes-osmocom/libosmo-abis/libosmo-abis.inc b/recipes-osmocom/libosmo-abis/libosmo-abis.inc
index dcfcbf7..955ebe3 100644
--- a/recipes-osmocom/libosmo-abis/libosmo-abis.inc
+++ b/recipes-osmocom/libosmo-abis/libosmo-abis.inc
@@ -2,13 +2,17 @@
 HOMEPAGE = "https://osmocom.org/projects/libosmo-abis"
 LICENSE = "AGPLv3"
 LIC_FILES_CHKSUM = "file://COPYING;md5=73f1eb20517c55bf9493b7dd6e480788"
-INC_PR="r0.${META_TELEPHONY_OSMO_INC}"
+INC_PR="r1.${META_TELEPHONY_OSMO_INC}"
 
 DEPENDS = "libosmocore ortp libtalloc"
-DEPENDS_append_geode = "dahdi-linux"
 
 inherit autotools pkgconfig
 
+PACKAGECONFIG ??= "\
+    dahdi \
+    "
+PACKAGECONFIG[dahdi] = "--enable-dahdi,--disable-dahdi,dahdi-linux,"
+
 PACKAGES =+ "libosmotrau libosmotrau-dev"
 
 FILES_libosmotrau = "${libdir}/libosmotrau${SOLIBS}"