ASoC: cs35l35: Constify struct regmap_config

`cs35l35_regmap` is not modified and can be declared as const to move
its data to a read-only section.

Signed-off-by: Javier Carrasco <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/codecs/cs35l35.c

···
 	.endianness		= 1,
 };
 
-static struct regmap_config cs35l35_regmap = {
+static const struct regmap_config cs35l35_regmap = {
 	.reg_bits = 8,
 	.val_bits = 8,