ALSA: isa: Add SPDX id lines to some files

ALSA: isa: Add SPDX id lines to some files

Add SPDX-License-Identifier lines to several files where
they are missing, mostly in the sound/isa subdir.
Use GPL-2.0 as the id.

[ note: the same change applied to sound/hda/core/trace.c, too -- tiwai ]

Signed-off-by: Tim Bird <tim.bird@sony.com>
Link: https://patch.msgid.link/20260212195905.3726149-1-tim.bird@sony.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>