smpp: Checking an array for NULL will always be false

The if (submit->short_message) and if (smsc->system_id) will
always be true.

Fixes: Coverity CID 1042371, CID 1042372
diff --git a/openbsc/src/libmsc/smpp_openbsc.c b/openbsc/src/libmsc/smpp_openbsc.c
index 1cbc4b0..e41d377 100644
--- a/openbsc/src/libmsc/smpp_openbsc.c
+++ b/openbsc/src/libmsc/smpp_openbsc.c
@@ -113,7 +113,7 @@
 		}
 		sms_msg = t->value.octet;
 		sms_msg_len = t->length;
-	} else if (submit->short_message && submit->sm_length) {
+	} else if (submit->sm_length) {
 		sms_msg = submit->short_message;
 		sms_msg_len = submit->sm_length;
 	} else {