ASoC: s6105-ipcam: Fix build for I2C dependencies

The s6105-ipcam driver calls i2c_register_board_info() which means that
not only does it need I2C to be enabled to be built but since that
symbol is not exported it means that the driver also can't be linked as
a module.  Use a bool instead of a tristate and add a dependency on I2C
to fix these issues.

Commit b5dd60fd (ASoC: s6000: Allow to build when COMPILE_TEST is
enabled) made this problem more visible since it enabled build of the
driver on more common architectures but this has always been an issue.
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/s6000/Kconfig

@@ -15,8 +15,9 @@ config SND_S6000_SOC_I2S
 	tristate
 
 config SND_S6000_SOC_S6IPCAM
-	tristate "SoC Audio support for Stretch 6105 IP Camera"
-	depends on SND_S6000_SOC
+	bool "SoC Audio support for Stretch 6105 IP Camera"
+	depends on SND_S6000_SOC=y
+	depends on I2C=y
 	depends on XTENSA_PLATFORM_S6105 || COMPILE_TEST
 	select SND_S6000_SOC_I2S
 	select SND_SOC_TLV320AIC3X