trx: fix dev-args issue

osmo_talloc_replace_string used by the vty needs a talloc string.

Change-Id: Ifed8fd42dc7464899de69985f3b5f5b47c88a7d1
diff --git a/CommonLibs/trx_vty.c b/CommonLibs/trx_vty.c
index 1878d83..55142ef 100644
--- a/CommonLibs/trx_vty.c
+++ b/CommonLibs/trx_vty.c
@@ -822,7 +822,7 @@
 	trx->cfg.rx_sps = DEFAULT_RX_SPS;
 	trx->cfg.filler = FILLER_ZERO;
 	trx->cfg.rssi_offset = 0.0f;
-	trx->cfg.dev_args = "";
+	trx->cfg.dev_args = talloc_strdup(trx, "");
 
 	return trx;
 }