drm/radeon: cleanup coding style a bit

Maybe no need to check ws before kmalloc, kmalloc will check
itself, kmalloc`s logic is if ptr is NULL, kmalloc will just
return

Reviewed-by: Christian König <[e-mail]>
Signed-off-by: Bernard Zhao <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/radeon/atom.c

···
 	SDEBUG("<<\n");
 
 free:
-	if (ws)
-		kfree(ectx.ws);
+	kfree(ectx.ws);
 	return ret;
 }