MAINTAINERS: Change Maintainer for some at91 drivers

I hand over the maintenance of these drivers to my colleagues. Claudiu,
Codrin and Tudor already have experience with these controllers and
sub-systems.

Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20200702134224.3750-1-nicolas.ferre@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.org>