gpio: remove VR41XX related gpio 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>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>