serial: remove VR41XX serial driver

Commit d3164e2f ("MIPS: Remove VR41xx support") removed support
for MIPS VR41xx platform, so remove exclusive drivers for this
platform, too.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Link: https://lore.kernel.org/r/20220715140322.135825-1-tsbogend@alpha.franken.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>