ASoC: codecs: ad193x: make two arrays static const, makes object smaller

Don't populate the arrays on the stack but instead make them
static const. Makes the object code smaller by 37 bytes.

Before:
   text	   data	    bss	    dec	    hex	filename
  16253	   7200	      0	  23453	   5b9d	sound/soc/codecs/ad193x.o

After:
   text	   data	    bss	    dec	    hex	filename
  16056	   7360	      0	  23416	   5b78	sound/soc/codecs/ad193x.o

(gcc version 9.2.1, amd64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20190906161404.1440-1-colin.king@canonical.com
Signed-off-by: Mark Brown <broonie@kernel.org>