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: NChristian König <christian.koenig@amd.com>
Signed-off-by: NBernard Zhao <bernard@vivo.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/atom.c

@@ -1211,8 +1211,7 @@ static int atom_execute_table_locked(struct atom_context *ctx, int index, uint32
 	SDEBUG("<<\n");
 
 free:
-	if (ws)
-		kfree(ectx.ws);
+	kfree(ectx.ws);
 	return ret;
 }