ALSA: usb-audio: Add missing kconfig dependecy

The commit 44dcbbb1 introduced the usage of bitreverse helpers but
forgot to add the dependency.  This patch adds the selection for
CONFIG_BITREVERSE.

Fixes: 44dcbbb1 ('ALSA: snd-usb: add support for bit-reversed byte formats')
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>