ASoC: rt5682: Fix build error without CONFIG_I2C

If I2C is n but SoundWire is m, building fails:

sound/soc/codecs/rt5682.c:3716:1: warning: data definition has no type or storage class
 module_i2c_driver(rt5682_i2c_driver);
 ^~~~~~~~~~~~~~~~~
sound/soc/codecs/rt5682.c:3716:1: error: type defaults to 'int' in declaration of 'module_i2c_driver' [-Werror=implicit-int]
sound/soc/codecs/rt5682.c:3716:1: warning: parameter names (without types) in function declaration

Guard this use #ifdef CONFIG_I2C.

Fixes: 5549ea64 ("ASoC: rt5682: fix unmet dependencies")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20200401091055.34112-1-yuehaibing@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/rt5682.c

@@ -3703,7 +3703,7 @@ static const struct acpi_device_id rt5682_acpi_match[] = {
 MODULE_DEVICE_TABLE(acpi, rt5682_acpi_match);
 #endif
 
-static struct i2c_driver rt5682_i2c_driver = {
+static struct i2c_driver __maybe_unused rt5682_i2c_driver = {
 	.driver = {
 		.name = "rt5682",
 		.of_match_table = of_match_ptr(rt5682_of_match),
@@ -3713,7 +3713,10 @@ static struct i2c_driver rt5682_i2c_driver = {
 	.shutdown = rt5682_i2c_shutdown,
 	.id_table = rt5682_i2c_id,
 };
+
+#ifdef CONFIG_I2C
 module_i2c_driver(rt5682_i2c_driver);
+#endif
 
 MODULE_DESCRIPTION("ASoC RT5682 driver");
 MODULE_AUTHOR("Bard Liao <bardliao@realtek.com>");