EDAC/highbank: Handover Calxeda Highbank maintenance to Andre Przywara

I do not have hardware anymore, nor there is ongoing development. So
handover maintenance to Andre who already maintains the last remainings
of Calxeda.

Signed-off-by: Robert Richter <rric@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Andre Przywara <andre.przywara@arm.com>
Link: https://lkml.kernel.org/r/20200824124931.2933-1-rric@kernel.org