ALSA: usb-audio: remove redundant assignment to variable c

The variable c is being initialized in an outer for-loop and also
re-initialized inside an inner for-loop. The first initialization
is redundant and can be removed.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220207140617.341172-1-colin.i.king@gmail.com


Signed-off-by: Takashi Iwai <tiwai@suse.de>