drm: fix drm_drv_uses_atomic_modeset on non modesetting drivers.

vgem seems to oops on the intel CI due to the vgem debugfs init
hitting this path now.

Check if we have mode_config funcs before checking one.

Signed-off-by: Dave Airlie <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

include/drm/drm_drv.h

···
 static inline bool drm_drv_uses_atomic_modeset(struct drm_device *dev)
 {
 	return drm_core_check_feature(dev, DRIVER_ATOMIC) ||
-		dev->mode_config.funcs->atomic_commit != NULL;
+		(dev->mode_config.funcs && dev->mode_config.funcs->atomic_commit != NULL);
 }