[ALSA] copy_ctl_value_from_user() warning fix

sound/core/control_compat.c: In function 'copy_ctl_value_from_user':
sound/core/control_compat.c:222: warning: 'count' may be used uninitialized in this function

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>