ALSA: bebob: Fix a missing to unlock mutex in error handling case

In error handling case, special_clk_ctl_put() returns without unlock_mutex(),
therefore the mutex is still locked. This commit moves mutex_lock() after
the error handling case.

This commit is my solution for this post.

[PATCH -next] ALSA: bebob: Fix missing unlock on error in special_clk_ctl_put()
https://lkml.org/lkml/2014/7/20/12

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
ALSA: bebob: Use different labels for digital input/output

This commit uses different labels for control elements of digital input/output
interfaces to correct my misunderstanding about M-Audio Firewire 1814 and
ProjectMix I/O.

According to user manuals for these two models, they have two modes for
digital input; one is S/PDIF in both of optical and coaxial interfaces,
another is ADAT in optical interface only.

But in current implementation, a control element for it reduced labels which
a control element for digital output uses because of my misunderstanding
that optical interface is not available for digital input with S/PDIF mode.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
ALSA: bebob: Correction for return value of .put callback

This commit is for correction of my misunderstanding about return value of
.put callback in ALSA Control interface.

According to 'Writing ALSA Driver' (*1), return value of the callback has
three patterns; 1: changed, 0: not changed, an negative value: fatal error.

But I misunderstood that it's boolean; zero or nonzero.

*1: Writing an ALSA Driver (2005, Takashi Iwai)
http://www.alsa-project.org/main/index.php/ALSA_Driver_Documentation

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
ALSA: bebob: Correction for return value of special_clk_ctl_put() in error

This commit is a supplement to my previous patch.
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-July/079190.html

The special_clk_ctl_put() still returns 0 in error handling case. It should
return -EINVAL.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>