ALSA: declare snd_kcontrol_new structures as const

Declare snd_kcontrol_new structures as const as they are only passed an
argument to the function snd_ctl_new1. This argument is of type const,
so snd_kcontrol_new structures having this property can be made const.
Done using Coccinelle:

@r disable optional_qualifier@
identifier x;
position p;
@@
static struct snd_kcontrol_new x@p={...};

@ok@
identifier r.x;
position p;
@@
snd_ctl_new1(&x@p,...)

@bad@
position p != {r.p,ok.p};
identifier r.x;
@@
x@p

@depends on !bad disable optional_qualifier@
identifier r.x;
@@
+const
struct snd_kcontrol_new x;

Cross compiled these files:
sound/aoa/codecs/tas.c - powerpc
sound/mips/{hal2.c/sgio2audio.c} - mips
sound/ppc/{awacs.c/beep.c/tumbler.c} - powerpc
sound/soc/sh/siu_dai.c - sh
Could not find an architecture to compile sound/sh/aica.c.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>