rtc: vr41xx: remove 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>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220715135330.134684-1-tsbogend@alpha.franken.de