arch/powerpc: Use RCU_INIT_POINTER(x, NULL) in platforms/cell/spu_syscalls.c

Here rcu_assign_pointer() is ensuring that the
initialization of a structure is carried out before storing a pointer
to that structure.
So, rcu_assign_pointer(p, NULL) can always safely be converted to
RCU_INIT_POINTER(p, NULL).
Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/cell/spu_syscalls.c

@@ -170,7 +170,7 @@ EXPORT_SYMBOL_GPL(register_spu_syscalls);
 void unregister_spu_syscalls(struct spufs_calls *calls)
 {
 	BUG_ON(spufs_calls->owner != calls->owner);
-	rcu_assign_pointer(spufs_calls, NULL);
+	RCU_INIT_POINTER(spufs_calls, NULL);
 	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(unregister_spu_syscalls);