regulator: max77857: Make max77857_id static

Fix sparse warning:
drivers/regulator/max77857-regulator.c:430:28: warning: symbol 'max77857_id' was not declared. Should it be static?

max77857_id is not used outside the source file. Make it static.
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Link: https://patch.msgid.link/20240801114536.472796-1-yuehaibing@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/max77857-regulator.c

@@ -427,7 +427,7 @@ static int max77857_probe(struct i2c_client *client)
 	return 0;
 }
 
-const struct i2c_device_id max77857_id[] = {
+static const struct i2c_device_id max77857_id[] = {
 	{ "max77831", ID_MAX77831 },
 	{ "max77857", ID_MAX77857 },
 	{ "max77859", ID_MAX77859 },