ASoC: wm8960: Depends on I2C

Now that this is directly user selectable it needs to care about its
dependencies.
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/codecs/Kconfig

@@ -910,6 +910,7 @@ config SND_SOC_WM8955
 
 config SND_SOC_WM8960
 	tristate "Wolfson Microelectronics WM8960 CODEC"
+	depends on I2C
 
 config SND_SOC_WM8961
 	tristate