The azx_pcm_hw structure is only copied into another structure,
so make it const.
The opportunity for this change was found using Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Link: https://lore.kernel.org/r/1577864614-5543-3-git-send-email-Julia.Lawall@inria.fr
Signed-off-by: Takashi Iwai <tiwai@suse.de>