Implement reads/writes MCH_RICM/MCH_DRD

* The BIOS tries to write to 0x1000f430/0x1000f440 which contain the
registers MCH_RICM/MCH_DRD. Saldy these registers are quite undocumented.
So the writing logic has been taken from PCSX2:
https://github.com/PCSX2/pcsx2/blob/master/pcsx2/HwWrite.cpp#L237
Forgive me, for I have sinned.