[PATCH v2] ASoC: wm8731: fix build when I2C is not enabled

[Randy Dunlap]

Building wm8731-i2c.c has a kconfig warning and build errors when
I2C is not enabled, so prevent that kconfig-uration.

WARNING: unmet direct dependencies detected for SND_SOC_WM8731_I2C
  Depends on [n]: SOUND [=y] && !UML && SND [=m] && SND_SOC [=m] && I2C [=n]
  Selected by [m]:
  - SND_SOC_DB1200 [=m] && SOUND [=y] && !UML && SND [=m] && SND_SOC [=m] && SND_SOC_AU1XPSC [=m]

and subsequent build errors:

../sound/soc/codecs/wm8731-i2c.c:64:1: warning: data definition has no type or storage class
   64 | module_i2c_driver(wm8731_i2c_driver);
../sound/soc/codecs/wm8731-i2c.c:64:1: error: type defaults to 'int' in declaration of 'module_i2c_driver' [-Werror=implicit-int]
../sound/soc/codecs/wm8731-i2c.c:64:1: warning: parameter names (without types) in function declaration
../sound/soc/codecs/wm8731-i2c.c:55:26: warning: 'wm8731_i2c_driver' defined but not used [-Wunused-variable]
   55 | static struct i2c_driver wm8731_i2c_driver = {

Fixes: 9dc15f81baf2 ("ASoC: wm8731: Factor out the I2C and SPI bus code into separate modules")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Liam Girdwood <lgirdwood@xxxxxxxxx>
Cc: alsa-devel@xxxxxxxxxxxxxxxx
Cc: Jaroslav Kysela <perex@xxxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxxx>
---
v2: add Takashi's email address

 sound/soc/au1x/Kconfig |    1 +
 1 file changed, 1 insertion(+)

diff sound/soc/au1x/Kconfig sound/soc/au1x/Kconfig
--- a/sound/soc/au1x/Kconfig
+++ b/sound/soc/au1x/Kconfig
@@ -54,6 +54,7 @@ config SND_SOC_DB1000
 config SND_SOC_DB1200
 	tristate "DB1200/DB1300/DB1550 Audio support"
 	depends on SND_SOC_AU1XPSC
+	depends on I2C
 	select SND_SOC_AU1XPSC_AC97
 	select SND_SOC_AC97_CODEC
 	select SND_SOC_WM9712