powerpc: Mark 4xx as Orphan in MAINTAINERS

The 4xx platforms are no longer maintained.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200224233146.23734-4-mpe@ellerman.id.au

MAINTAINERS

@@ -9644,11 +9644,8 @@ F:	arch/powerpc/platforms/512x/
 F:	arch/powerpc/platforms/52xx/
 
 LINUX FOR POWERPC EMBEDDED PPC4XX
-M:	Alistair Popple <alistair@popple.id.au>
-M:	Matt Porter <mporter@kernel.crashing.org>
-W:	http://www.penguinppc.org/
 L:	linuxppc-dev@lists.ozlabs.org
-S:	Maintained
+S:	Orphan
 F:	arch/powerpc/platforms/40x/
 F:	arch/powerpc/platforms/44x/