ALSA: firewire-motu: remove invalid bitshift for register value

In protocol version 3, drivers can read current sampling clock status from
register 0x'ffff'f000'0b14. 8 bits of LSB of this register represents type
of signal as source of clock.

Current driver code includes invalid bitshift to handle the parameter. This
commit fixes the bug.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 5992e300 ("ALSA: firewire-motu: add support for MOTU 828mk3 (FireWire/Hybrid) as a model with protocol version 3")
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>