pdch: Avoid sending GSMTAP_CHANNEL_UNKOWN for rejected UL EGPRS data block

Even if we don't accept it, let's submit GSMTAP with correct channel.
We don't return error like in code below, because otherwise the generic
UNKNOWN gsmtap message will be sent.

Change-Id: I853679ce8907d46fcb84ae4127335c10623f09c9
diff --git a/src/pdch.cpp b/src/pdch.cpp
index f46acc8..77be1b5 100644
--- a/src/pdch.cpp
+++ b/src/pdch.cpp
@@ -793,14 +793,14 @@
 	 * control blocks (see 44.060, section 10.3, 1st par.)
 	 */
 	if (mcs_is_edge(cs)) {
+		bts()->send_gsmtap(PCU_GSMTAP_C_UL_DATA_EGPRS, true, trx_no(), ts_no, GSMTAP_CHANNEL_PDTCH, fn,
+				   data, data_len);
 		if (!bts()->bts_data()->egprs_enabled) {
 			LOGP(DRLCMACUL, LOGL_ERROR,
 				"Got %s RLC block but EGPRS is not enabled\n",
 				mcs_name(cs));
-			return -EINVAL;
+			return 0;
 		}
-		bts()->send_gsmtap(PCU_GSMTAP_C_UL_DATA_EGPRS, true, trx_no(), ts_no, GSMTAP_CHANNEL_PDTCH, fn,
-				   data, data_len);
 	} else {
 		bts()->send_gsmtap(PCU_GSMTAP_C_UL_DATA_GPRS, true, trx_no(), ts_no, GSMTAP_CHANNEL_PDTCH, fn,
 				   data, data_len);