libosmo-abis: Revert parts of the multi-TRX support in libosmo-abis

The line doesn't have the signalling type set yet. It will be set
_after_ the rsl connection is considered up. This is addressing
RSL Connection failures like:

<0001> oml.c:1026 Rx IPA RSL CONNECT IP=1.2.3.4 PORT=3003 STREAM=0x00
<000f> input/ipaccess.c:921 cannot create RSL BTS link: trx_nr (0) does not refer to a signalling link
<0001> oml.c:1030 Error in abis_open(RSL): -22
<0001> oml.c:341 Sending FOM NACK with cause Message cannot be performed.
diff --git a/recipes-osmocom/libosmo-abis/files/fix-rsl-connect.patch b/recipes-osmocom/libosmo-abis/files/fix-rsl-connect.patch
new file mode 100644
index 0000000..63c5052
--- /dev/null
+++ b/recipes-osmocom/libosmo-abis/files/fix-rsl-connect.patch
@@ -0,0 +1,21 @@
+The line is not initiliazed to E1INP_TS_TYPE_SIGN by default
+
+diff --git a/src/input/ipaccess.c b/src/input/ipaccess.c
+index 145e471..49424e7 100644
+--- a/src/input/ipaccess.c
++++ b/src/input/ipaccess.c
+@@ -915,12 +915,14 @@ int e1inp_ipa_bts_rsl_connect_n(struct e1inp_line *line,
+ 			"trx_nr (%d) out of range\n", trx_nr);
+ 		return -EINVAL;
+ 	}
++/*
+ 	if (line->ts[E1INP_SIGN_RSL+trx_nr-1].type != E1INP_TS_TYPE_SIGN) {
+ 		LOGP(DLINP, LOGL_ERROR, "cannot create RSL BTS link: "
+ 			"trx_nr (%d) does not refer to a signalling link\n",
+ 			trx_nr);
+ 		return -EINVAL;
+ 	}
++*/
+ 
+ 	rsl_link = ipa_client_conn_create(tall_ipa_ctx,
+ 					  &line->ts[E1INP_SIGN_RSL+trx_nr-1],