ASoC: Constify reg_default tables

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Peter Rosin <peda@axentia.se>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/sound/soc/codecs/isabelle.c b/sound/soc/codecs/isabelle.c
index ebd9028..ac7dfe7 100644
--- a/sound/soc/codecs/isabelle.c
+++ b/sound/soc/codecs/isabelle.c
@@ -33,7 +33,7 @@
 
 
 /* Register default values for ISABELLE driver. */
-static struct reg_default isabelle_reg_defs[] = {
+static const struct reg_default isabelle_reg_defs[] = {
 	{ 0, 0x00 },
 	{ 1, 0x00 },
 	{ 2, 0x00 },