pkggrp-ni-extra: remove python3-mprpc
pkggrp-ni-extra: remove python3-mprpc

The mprpc module has been deprecated upstream. The NI RFMI team is
already aware of the deprecation and tracking the work to move their
drivers to use gRPC.

Remove the dependency, because it is unbuildable in hardknott.

Signed-off-by: Alex Stewart <04cdb2793e4fb0120cc30d1c823099f3862701f4@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt