MAINTAINERS: Update PowerPC 4xx tree

Move the powerpc-4xx.git tree back to kernel.org
Signed-off-by: NJosh Boyer <jwboyer@gmail.com>

MAINTAINERS

@@ -4034,7 +4034,7 @@ M:	Josh Boyer <jwboyer@gmail.com>
 M:	Matt Porter <mporter@kernel.crashing.org>
 W:	http://www.penguinppc.org/
 L:	linuxppc-dev@lists.ozlabs.org
-T:	git git://git.infradead.org/users/jwboyer/powerpc-4xx.git
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/jwboyer/powerpc-4xx.git
 S:	Maintained
 F:	arch/powerpc/platforms/40x/
 F:	arch/powerpc/platforms/44x/