TT#108003 Fix off-by-one check dtmf_samples()

The dtmf_freqs array contains one less element than the check was
allowing for.

Change-Id: I783fa6bcd0bd79fad9886ee53e7a990e504ecff8
Warned-by: coverity

lib/dtmflib.c

@@ -47,7 +47,7 @@ void dtmf_samples(void *buf, unsigned long offset, unsigned long num, unsigned i
 		return;
 	}
 
-	if (event > G_N_ELEMENTS(dtmf_freqs)) {
+	if (event >= G_N_ELEMENTS(dtmf_freqs)) {
 		ilog(LOG_WARN | LOG_FLAG_LIMIT, "Unsupported DTMF event %u", event);
 		memset(buf, 0, num * 2);
 		return;