bts: fix uninitialized memaccess in BTS::send_gsmtap()

Change-Id: I7c5105c9e8a2c680dc8b24cc5e3bda6f7405a3ee
Fixes: CID#216511
diff --git a/src/bts.cpp b/src/bts.cpp
index 87afc9f..307df94 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -529,7 +529,7 @@
 		      uint8_t ts_no, uint8_t channel, uint32_t fn,
 		      const uint8_t *data, unsigned int len)
 {
-	struct pcu_l1_meas meas;
+	struct pcu_l1_meas meas = { 0 };
 	send_gsmtap_meas(categ, uplink, trx_no, ts_no, channel, fn, data, len, &meas);
 }