bts: Fix misleading log line in bts_rcv_rach()

If it's not single block packets access, then it's one phase packet
access. TS 44.018 Table 9.1.8.1:
"""
One phase packet access with request for single timeslot uplink transmission;
one PDCH is needed.
"""

Change-Id: Ic6beb6dcfebb77fd264b179b028f99a29c644fb1
diff --git a/src/bts.cpp b/src/bts.cpp
index 50df92e..bd1366e 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -900,8 +900,8 @@
 	if (chan_req.single_block)
 		LOGP(DRLCMAC, LOGL_DEBUG, "MS requests single block allocation\n");
 	else if (bts->pcu->vty.force_two_phase) {
-		LOGP(DRLCMAC, LOGL_DEBUG, "MS requests single block allocation, "
-		     "but we force two phase access\n");
+		LOGP(DRLCMAC, LOGL_DEBUG, "MS requests single TS uplink transmission "
+		     "(one phase packet access), but we force two phase access\n");
 		chan_req.single_block = true;
 	}