An array of templates for control element set is passed as an
argument for snd_hda_add_new_ctls(). This argument has 'const'
qualifier therefore the passed array can have the qualifier.

This commit adds this optimization.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>