ALSA: ice1712: add const to snd_akm4xxx structures

Declare snd_akm4xxx structures  as const as they are only passed
to the function snd_ice1712_akm4xxx_init. This argument is of type
const, so make the structures const.
Done using Coccinelle:

@match disable optional_qualifier@
identifier s;
position p;
@@
static struct snd_akm4xxx s@p={...};

@good1@
identifier match.s;
position p;
@@
snd_ice1712_akm4xxx_init(...,&s@p,...)

@bad@
identifier match.s;
position p!={match.p,good1.p};
@@
s@p

@depends on !bad disable optional_qualifier@
identifier match.s;
@@
static
+const
struct snd_akm4xxx s={...};

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>