vga-switcheroo: select VGA arbitration.

Since Matthew's changes we have to select arbitration.

Reported-by: devh on #radeon
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/vga/Kconfig

@@ -21,6 +21,7 @@ config VGA_SWITCHEROO
 	bool "Laptop Hybrid Graphics - GPU switching support"
 	depends on X86
 	depends on ACPI
+	select VGA_ARB
 	help
 	  Many laptops released in 2008/9/10 have two GPUs with a multiplexer
 	  to switch between them. This adds support for dynamic switching when