[ALSA] rme9652 - Fix the hw_pointer check

The negative check in hw_pointer callback doesn't work because the
value is unsigned.  Cast to int in the comparison to fix this.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@suse.cz>

sound/pci/rme9652/rme9652.c

@@ -406,7 +406,7 @@ static snd_pcm_uframes_t rme9652_hw_pointer(struct snd_rme9652 *rme9652)
 		} else if (!frag)
 			return 0;
 		offset -= rme9652->max_jitter;
-		if (offset < 0)
+		if ((int)offset < 0)
 			offset += period_size * 2;
 	} else {
 		if (offset > period_size + rme9652->max_jitter) {