[ALSA] caiaq - misc input handling fixes

 - link input device with its parent so that it placed in proper spot
   in sysfs hierarchy
 - drivers that allow changing their keymaps should use private copy
   of the keymap so that one instance of a device does not affect
   another instance
 - it is preferred for drivers to properly set up input_dev->phys to
   help userspace locate devices
 - drivers should use usb_to_input_id(), or perform endianess conversion,
   themselves, otherwise ID is not correct on big-endian boxes
 - whitespace and formatting cleanup
Acked-by: Daniel Mack <daniel@caiaq.de>

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>