ALSA: firewire-lib: remove reference counting

ALSA: firewire-lib: remove reference counting

commit c6f224dc20ad959175c2dfec70b5a61c6503a793 upstream.

AMDTP helper functions increment/decrement reference counter for an
instance of FireWire unit, while it's complicated for each driver to
process error state.

In previous commit, each driver has the role of reference counting. This
commit removes this role from the helper function.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>