ASoC: rt5659: declare rt5659_i2c_driver static

Declar rt5659_i2c_driver, which is only being passed to
module_i2c_driver(rt5659_i2c_driver), static.

Fixes: commit d3cb2de2 ("ASoC: rt5659: add rt5659 codec driver")
Signed-off-by: NNicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/codecs/rt5659.c

@@ -4230,7 +4230,7 @@ static struct acpi_device_id rt5659_acpi_match[] = {
 MODULE_DEVICE_TABLE(acpi, rt5659_acpi_match);
 #endif
 
-struct i2c_driver rt5659_i2c_driver = {
+static struct i2c_driver rt5659_i2c_driver = {
 	.driver = {
 		.name = "rt5659",
 		.owner = THIS_MODULE,