docs(maintainers): update NPU driver files

New files have been added for the Arm(R) Ethos(TM)-N NPU driver with the
addition of TZMP1 support so the files in the maintainers list have been
updated accordingly.

Signed-off-by: Mikael Olsson <mikael.olsson@arm.com>
Change-Id: I3768b2ab78c117c1dd4fc03b38cf35f6811fa378
1 file changed