[ALSA] pcm_lib: fix sparse warning about different signedness

pcm_lib: fix sparse warning about different signedness
Signed-off-by: NMarcin Ślusarz <marcin.slusarz@gmail.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>

sound/core/pcm_lib.c

@@ -1139,7 +1139,7 @@ EXPORT_SYMBOL(snd_pcm_hw_constraint_step);
 
 static int snd_pcm_hw_rule_pow2(struct snd_pcm_hw_params *params, struct snd_pcm_hw_rule *rule)
 {
-	static int pow2_sizes[] = {
+	static unsigned int pow2_sizes[] = {
 		1<<0, 1<<1, 1<<2, 1<<3, 1<<4, 1<<5, 1<<6, 1<<7,
 		1<<8, 1<<9, 1<<10, 1<<11, 1<<12, 1<<13, 1<<14, 1<<15,
 		1<<16, 1<<17, 1<<18, 1<<19, 1<<20, 1<<21, 1<<22, 1<<23,