ARM: renesas: Update MAINTAINERS file

Update MAINTAINERS file. Add missing MAINTAINERS file for Spider,
Whitehawk and V3HSK boards. Update mail addresses. Add file globs
to match on DT and driver files related to these boards.

The GRPEACH and R2DPLUS are special in that they are not R-Car
and have their own set of specialized drivers.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>