MAINTAINERS: Change my email address

The old address is no longer valid. Use the my new one instead.

Signed-off-by: John Crispin <john@phrozen.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13200/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>