thermal: add the support for building the generic thermal as a module

Build the generic thermal driver as module "thermal_sys".

Make ACPI thermal, video, processor and fan SELECT the generic
thermal driver, as these drivers rely on it to build the sysfs I/F.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index b4f5e85..c52fca8 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -140,6 +140,7 @@
 	tristate "Video"
 	depends on X86 && BACKLIGHT_CLASS_DEVICE && VIDEO_OUTPUT_CONTROL
 	depends on INPUT
+	select THERMAL
 	help
 	  This driver implement the ACPI Extensions For Display Adapters
 	  for integrated graphics devices on motherboard, as specified in
@@ -151,6 +152,7 @@
 
 config ACPI_FAN
 	tristate "Fan"
+	select THERMAL
 	default y
 	help
 	  This driver adds support for ACPI fan devices, allowing user-mode 
@@ -172,6 +174,7 @@
 
 config ACPI_PROCESSOR
 	tristate "Processor"
+	select THERMAL
 	default y
 	help
 	  This driver installs ACPI as the idle handler for Linux, and uses