ASoC: AMD: constify regulator_desc structure

The regulator_desc structure can be const as it is only passed as the
second argument of devm_regulator_register and the corresponding
parameter is declared as const.

Done with the help of Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/amd/acp-da7219-max98357a.c

@@ -403,7 +403,7 @@ static struct regulator_config acp_da7219_cfg = {
 static struct regulator_ops acp_da7219_ops = {
 };
 
-static struct regulator_desc acp_da7219_desc = {
+static const struct regulator_desc acp_da7219_desc = {
 	.name = "reg-fixed-1.8V",
 	.type = REGULATOR_VOLTAGE,
 	.owner = THIS_MODULE,