mfd: Don't allow WM8350 to be built modular

The genirq implementation does not allow modules to implement irq_chips
so the conversion of WM8350 to genirq means we can no longer allow the
driver to be built as a module.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index b670d10..d957373 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -205,7 +205,7 @@
 	  functionality of the device.
 
 config MFD_WM8350
-	tristate
+	bool
 
 config MFD_WM8350_CONFIG_MODE_0
 	bool
@@ -256,9 +256,9 @@
 	depends on MFD_WM8350
 
 config MFD_WM8350_I2C
-	tristate "Support Wolfson Microelectronics WM8350 with I2C"
+	bool "Support Wolfson Microelectronics WM8350 with I2C"
 	select MFD_WM8350
-	depends on I2C
+	depends on I2C=y
 	help
 	  The WM8350 is an integrated audio and power management
 	  subsystem with watchdog and RTC functionality for embedded