ASoC: doc: Update dead links

The alsa-project documentation is now part of the kernel docs,
the original links are long dead, update links.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Mark Brown <broonie@kernel.org>
Cc: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20220628165807.152191-1-marex@denx.de


Signed-off-by: Mark Brown <broonie@kernel.org>