pcu_l1_if: Don't use GSMTAP_CHANNEL_PACCH when sending unknown gsmtap blocks

It's actually counter-productive when analyzing wireshark traces, since
one may not spot a decoding issue and assume PACCH is sent on the wrong
TS.

Change-Id: I7a96148f1ca1ebfa88a3ff714ea3bb8798866046
diff --git a/src/pcu_l1_if.cpp b/src/pcu_l1_if.cpp
index 37a0705..30d22bd 100644
--- a/src/pcu_l1_if.cpp
+++ b/src/pcu_l1_if.cpp
@@ -347,7 +347,7 @@
 
 	if (rc < 0 && (bts->gsmtap_categ_mask & (1 <<PCU_GSMTAP_C_UL_UNKNOWN))) {
 		gsmtap_send(bts->gsmtap, data_ind->arfcn | GSMTAP_ARFCN_F_UPLINK, data_ind->ts_nr,
-			    GSMTAP_CHANNEL_PACCH, 0, data_ind->fn, 0, 0, data_ind->data, data_ind->len);
+			    GSMTAP_CHANNEL_UNKNOWN, 0, data_ind->fn, 0, 0, data_ind->data, data_ind->len);
 	}
 
 	return rc;