drm/amdgpu: Drop DRIVER_USE_AGP

This doesn't do anything except auto-init drm_agp support when you
call drm_get_pci_dev(). Which amdgpu stopped doing with

commit b58c113
Author: Alex Deucher <[email protected]>
Date:   Fri Jun 2 17:16:31 2017 -0400

    drm/amdgpu: drop deprecated drm_get_pci_dev and drm_put_dev

No idea whether this was intentional or accidental breakage, but I
guess anyone who manages to boot a this modern gpu behind an agp
bridge deserves a price. A price I never expect anyone to ever collect
:-)

Cc: Alex Deucher <[email protected]>
Cc: "Christian König" <[email protected]>
Cc: Hawking Zhang <[email protected]>
Cc: Xiaojie Yuan <[email protected]>
Cc: Evan Quan <[email protected]>
Cc: "Tianci.Yin" <[email protected]>
Cc: "Marek Olšák" <[email protected]>
Cc: Hans de Goede <[email protected]>
Reviewed-by: Emil Velikov <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
Cc: [email protected]

Author: danvet

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

@@ -1389,7 +1389,7 @@ amdgpu_get_crtc_scanout_position(struct drm_device *dev, unsigned int pipe,
 
 static struct drm_driver kms_driver = {
 	.driver_features =
-	    DRIVER_USE_AGP | DRIVER_ATOMIC |
+	    DRIVER_ATOMIC |
 	    DRIVER_GEM |
 	    DRIVER_RENDER | DRIVER_MODESET | DRIVER_SYNCOBJ |
 	    DRIVER_SYNCOBJ_TIMELINE,