regulator: ltc3589: Constify ltc3589_reg_defaults

ltc3589_reg_defaults[] is not modified after initialized, so make it const.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/regulator/ltc3589.c b/drivers/regulator/ltc3589.c
index 0ce8e4e..c31dfa8 100644
--- a/drivers/regulator/ltc3589.c
+++ b/drivers/regulator/ltc3589.c
@@ -378,7 +378,7 @@
 	return false;
 }
 
-static struct reg_default ltc3589_reg_defaults[] = {
+static const struct reg_default ltc3589_reg_defaults[] = {
 	{ LTC3589_SCR1,   0x00 },
 	{ LTC3589_OVEN,   0x00 },
 	{ LTC3589_SCR2,   0x00 },