Allow VTY-based configuration of T3105

This timer will only be forwarded to BS11 and Ericsson Abis so far,
not to Nokia and ip.access BTS yet.
diff --git a/openbsc/src/libbsc/bts_siemens_bs11.c b/openbsc/src/libbsc/bts_siemens_bs11.c
index 2514d99..101e996 100644
--- a/openbsc/src/libbsc/bts_siemens_bs11.c
+++ b/openbsc/src/libbsc/bts_siemens_bs11.c
@@ -357,6 +357,9 @@
 	uint8_t arfcn_low = bts->c0->arfcn & 0xff;
 	uint8_t arfcn_high = (bts->c0->arfcn >> 8) & 0x0f;
 
+	/* T3105 attribute in units of 10ms */
+	bs11_attr_bts[2] = bts->network->T3105 / 10;
+
 	/* patch ARFCN into BTS Attributes */
 	bs11_attr_bts[69] &= 0xf0;
 	bs11_attr_bts[69] |= arfcn_high;