Thermal: build cpu_cooling code into thermal_sys module

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Eduardo Valentin <eduardo.valentin@ti.com>
Acked-by: Durgadoss R <durgadoss.r@intel.com>
diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index fb0672b..d1c2160 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -67,7 +67,7 @@
 	  Enable this to let the user space manage the platform thermals.
 
 config CPU_THERMAL
-	tristate "generic cpu cooling support"
+	bool "generic cpu cooling support"
 	depends on CPU_FREQ
 	select CPU_FREQ_TABLE
 	help