alloc_algorithm_b: For type 1 MS, limit number of donwlink TS to 5

The algorithm does not support more than 5 TS on downlink for type 1 MS.
Supporting more than 5 TS would require adding more complexity to this
algorithm. MS that support more than 4 (or 5) TS on downlink are rare,
if they really exist.
diff --git a/src/gprs_rlcmac_ts_alloc.cpp b/src/gprs_rlcmac_ts_alloc.cpp
index d2ccda9..a4e247a 100644
--- a/src/gprs_rlcmac_ts_alloc.cpp
+++ b/src/gprs_rlcmac_ts_alloc.cpp
@@ -235,6 +235,12 @@
 				"window reached maximum alowed Rx size\n");
 			break;
 		}
+		if (ms_type == 1 && rx_window_size == 5) {
+			LOGP(DRLCMAC, LOGL_DEBUG, "- Done, because slots / "
+				"window reached maximum supported Rx size of "
+				"this algorithm\n");
+			break;
+		}
 	}
 
 	LOGP(DRLCMAC, LOGL_DEBUG, "- Selected slots for RX: "