ALSA: usb-audio: fix combine_word problem

Fix combine_word problem where first octet is not
read properly. The only affected place seems to be the
INPUT_TERMINAL type. Before now, sound controls can be created
with the output terminal's name which is a fallback mechanism
used only for unknown input terminal types. For example,
Line can wrongly appear as Speaker. After the change it
should appear as Line.

	The side effect of this change can be that users
can expect the wrong control name in their scripts or
programs while now we return the correct one.

	Probably, these defines should use get_unaligned_le16 and
friends.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>