MAINTAINERS: Drop my "+dt" sub-address

I never really implemented any filtering on the "+dt" sub-address, so
drop it.

Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com> # for I2C
Link: https://lore.kernel.org/r/20240122211528.1719994-1-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>