ALSA: Cleanup redundant tests on unsigned

The variables are unsigned so the test `>= 0' is always true,
the `< 0' test always fails. In these cases the other part of
the test catches wrapped values.

In dac_audio_write() there does not occur a test for wrapped
values, but the test appears redundant.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/oss/sh_dac_audio.c

@@ -164,9 +164,6 @@ static ssize_t dac_audio_write(struct file *file, const char *buf, size_t count,
 	int free;
 	int nbytes;
 
-	if (count < 0)
-		return -EINVAL;
-
 	if (!count) {
 		dac_audio_sync();
 		return 0;