ALSA: us122l: clean up US144 handling

Use the device-id table and a private flag to determine the device type
(US122 or US144) rather than spreading product-id conditionals
throughout the driver.

This USB driver currently depends on X86 (why?), but we should still add
the missing endianness conversions when accessing the USB
device-descriptor fields.

Compile-tested only.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>