gpu/stub: fix acpi_video build error, fix stub kconfig dependencies

The comments under "config STUB_POULSBO" are close to correct,
but they are not being followed.  This patch updates them to reflect
the requirements for THERMAL.

This build error is caused by STUB_POULSBO selecting ACPI_VIDEO
when ACPI_VIDEO's config requirements are not met.

ERROR: "thermal_cooling_device_register" [drivers/acpi/video.ko] undefined!
ERROR: "thermal_cooling_device_unregister" [drivers/acpi/video.ko] undefined!
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/stub/Kconfig

 config STUB_POULSBO
 	tristate "Intel GMA500 Stub Driver"
 	depends on PCI
+	depends on NET # for THERMAL
 	# Poulsbo stub depends on ACPI_VIDEO when ACPI is enabled
 	# but for select to work, need to select ACPI_VIDEO's dependencies, ick
 	select BACKLIGHT_CLASS_DEVICE if ACPI
 	select INPUT if ACPI
 	select ACPI_VIDEO if ACPI
+	select THERMAL if ACPI
 	help
 	  Choose this option if you have a system that has Intel GMA500
 	  (Poulsbo) integrated graphics. If M is selected, the module will