MAINTAINERS: Split Cavium EDAC entry and add myself

Split the Cavium EDAC entry into MIPS and ARM drivers because
they have different maintainers and mailing lists.

Add myself as additional maintainer to the ThunderX driver.

Signed-off-by: Jan Glauber <jglauber@cavium.com>
Cc: David Daney <david.daney@cavium.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Sergey Temerkhanov <s.temerkhanov@gmail.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20171019064129.5064-1-jglauber@cavium.com


Signed-off-by: Borislav Petkov <bp@suse.de>