Don't populate the const arrays on the stack but instead make
it static. Makes the object code smaller, for example:

Before:
   text    data     bss     dec     hex filename
  14107    8832     224   23163    5a7b bytcht_es8316.o

After:
   text    data     bss     dec     hex filename
  14015    8896     224   23135    5a5f bytcht_es8316.o

(gcc version 8.2.0 x86_64)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>