drm/kms: fix Kconfig for new drivers.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/mgag200/Kconfig b/drivers/gpu/drm/mgag200/Kconfig
index ffffafa..d630134 100644
--- a/drivers/gpu/drm/mgag200/Kconfig
+++ b/drivers/gpu/drm/mgag200/Kconfig
@@ -5,6 +5,7 @@
 	select FB_SYS_COPYAREA
 	select FB_SYS_IMAGEBLIT
 	select DRM_KMS_HELPER
+	select DRM_TTM
 	help
 	 This is a KMS driver for the MGA G200 server chips, it
          does not support the original MGA G200 or any of the desktop