ALSA: firewire: Remove some left-over license text in sound/firewire

There is already a SPDX-License-Identifier tag, so the corresponding license
text can be removed.

While at it, be more consistent and:
- add a missing .c (ff-protocol-latter)
- remove an empty line (motu-protocol-v1)

Signed-off-by: Christophe JAILLET <[e-mail]>
Link: https://lore.kernel.org/r/2bfe76c7ee[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/firewire/dice/dice-harman.c

···
 // dice-harman.c - a part of driver for DICE based devices
 //
 // Copyright (c) 2021 Takashi Sakamoto
-//
-// Licensed under the terms of the GNU General Public License, version 2.
 
 #include "dice.h"
 

sound/firewire/dice/dice-presonus.c

···
 // dice-presonus.c - a part of driver for DICE based devices
 //
 // Copyright (c) 2019 Takashi Sakamoto
-//
-// Licensed under the terms of the GNU General Public License, version 2.
 
 #include "dice.h"
 

sound/firewire/fireface/ff-protocol-former.c

···
 // ff-protocol-former.c - a part of driver for RME Fireface series
 //
 // Copyright (c) 2019 Takashi Sakamoto
-//
-// Licensed under the terms of the GNU General Public License, version 2.
 
 #include <linux/delay.h>
 

sound/firewire/fireface/ff-protocol-latter.c

···
 // SPDX-License-Identifier: GPL-2.0
-// ff-protocol-latter - a part of driver for RME Fireface series
+// ff-protocol-latter.c - a part of driver for RME Fireface series
 //
 // Copyright (c) 2019 Takashi Sakamoto
-//
-// Licensed under the terms of the GNU General Public License, version 2.
 
 #include <linux/delay.h>
 

sound/firewire/motu/motu-protocol-v1.c

···
 // SPDX-License-Identifier: GPL-2.0-only
-
 // motu-protocol-v1.c - a part of driver for MOTU FireWire series
 //
 // Copyright (c) 2021 Takashi Sakamoto <[e-mail]>
-//
-// Licensed under the terms of the GNU General Public License, version 2.
 
 #include "motu.h"