drm: Move atomic_state_put after locks are dropped

drm_atomic_state_put doesn't require any locking, and this makes things
easier for switching to modeset_lock_all helpers in a future patch

Changes in v2:
- Moved state->acquire_ctx clear to a separate patch (Daniel)

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

drivers/gpu/drm/drm_atomic_helper.c

···
 		drm_modeset_backoff(&ctx);
 	}
 
-	drm_atomic_state_put(state);
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
+	drm_atomic_state_put(state);
 
 	return err;
 }