[ALSA] ac97_codec - trivial fix for bit update functions

This patch fixes a couple of bit update functions in
alsa-kernel/pci/ac97/ac97_codec.c, which could possibly corrupt bits not
in the given mask.
Specifically, it'll clobber unset bits in the target that are not in the
mask, when the corresponding bit in the given new value is set.
Signed-off-by: NJames C Georgas <jgeorgas@rogers.com>
Signed-off-by: NJaroslav Kysela <perex@suse.cz>

sound/pci/ac97/ac97_codec.c

@@ -382,7 +382,7 @@ int snd_ac97_update_bits_nolock(struct snd_ac97 *ac97, unsigned short reg,
 	unsigned short old, new;
 
 	old = snd_ac97_read_cache(ac97, reg);
-	new = (old & ~mask) | value;
+	new = (old & ~mask) | (value & mask);
 	change = old != new;
 	if (change) {
 		ac97->regs[reg] = new;
@@ -399,7 +399,7 @@ static int snd_ac97_ad18xx_update_pcm_bits(struct snd_ac97 *ac97, int codec, uns
 
 	mutex_lock(&ac97->page_mutex);
 	old = ac97->spec.ad18xx.pcmreg[codec];
-	new = (old & ~mask) | value;
+	new = (old & ~mask) | (value & mask);
 	change = old != new;
 	if (change) {
 		mutex_lock(&ac97->reg_mutex);