sms_queue.c: Improve misleading log line

Otherwise when read in a log file it seems it's really going to send 20
sms even if there's none to send.

Change-Id: Ieb9bb61a90f295d2ba5fb67a2abee2d30785876d
diff --git a/src/libmsc/sms_queue.c b/src/libmsc/sms_queue.c
index 6346c1d..d60cb4a 100644
--- a/src/libmsc/sms_queue.c
+++ b/src/libmsc/sms_queue.c
@@ -256,7 +256,7 @@
 	unsigned long long first_sub = 0;
 	int attempted = 0, rounds = 0;
 
-	LOGP(DLSMS, LOGL_DEBUG, "Attempting to send %d SMS\n", attempts);
+	LOGP(DLSMS, LOGL_DEBUG, "Attempting to send up to %d SMS\n", attempts);
 
 	do {
 		struct gsm_sms_pending *pending;