ALSA: usb-audio: Sanity checks for each pipe and EP types

The recent USB core code performs sanity checks for the given pipe and
EP types, and it can be hit by manipulated USB descriptors by syzbot.
For making syzbot happier, this patch introduces a local helper for a
sanity check in the driver side and calls it at each place before the
message handling, so that we can avoid the WARNING splats.

Reported-by:  <syzbot+d952e5e28f5fb7718d23@syzkaller.appspotmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>