mfd: intel_soc_pmic_chtwc: Turn Kconfig option into a bool

The PMIC provides ACPI OpRegions which must be available for other
drivers' PS0 / PS3 methods early-on as such it must be builtin as the
Kconfig help text already states.

Somehow its Kconfig option ended up being a tristate though, this fixes
this.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/Kconfig

@@ -495,7 +495,7 @@ config INTEL_SOC_PMIC_BXTWC
 	  on these systems.
 
 config INTEL_SOC_PMIC_CHTWC
-	tristate "Support for Intel Cherry Trail Whiskey Cove PMIC"
+	bool "Support for Intel Cherry Trail Whiskey Cove PMIC"
 	depends on ACPI && HAS_IOMEM && I2C=y && COMMON_CLK
 	depends on X86 || COMPILE_TEST
 	select MFD_CORE