x7 MBC3 RTC implementation bugs

[JL2210]

The Everdrive GB x7's MBC3 RTC implementation has some bugs.

with this testROM: https://github.com/aaaaaa123456789/rtc3test/tree/develop

the following tests fail:

(basic tests all pass)

range tests:
all bits clear pass
all bits set fail
valid bits (fluctuate between pass, fail h, and fail hs)
invalid value tick (fluctuate between fail and n/a)
invalid rollovers n/a
high minutes fail
high hours fail

sub-second writes:
rtcs/500 (~500.0ms)
rtcs/900 (~900.0ms)
rtc off/400 (~900.0ms)

to quote the developer on the first two sub-second writes tests:

the correct results are 1000.0ms
because writing to RTCS should reset the sub-second counter

also note:

In DMG mode, passes are black, fails are gray

of course, these all pass on an original MBC3

[TheShadowRunner]

You might want to reach @krikzz on Twitter to make sure he sees this.