Update the function immediate assignment for EGPRS

Encode the EGPRS fields of immediate assignment message in uplink
when EGPRS PACKET CHANNEL REQUEST (11 bit RACH) is received.
The series of patches for 11 bit RACH are dependent on libosmocore
and osmo-bts patches for 11 bit RACH.

Change-Id: Ie5e309156e5dbbb6add74a1b4d257c4ee2332e52
diff --git a/src/bts.cpp b/src/bts.cpp
index 015bf9f..73ec1f7 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -556,7 +556,7 @@
 	plen = Encoding::write_immediate_assignment(
 		tbf, immediate_assignment, 0, ra, Fn, ta,
 		m_bts.trx[trx_no].arfcn, ts_no, tsc, usf, 0, sb_fn,
-		m_bts.alpha, m_bts.gamma, -1);
+		m_bts.alpha, m_bts.gamma, -1, burst_type, sb);
 
 	if (plen >= 0) {
 		pcu_l1if_tx_agch(immediate_assignment, plen);