Emulate GameCube memory card speeds

Fixes http://code.google.com/p/dolphin-emu/issues/detail?id=2284

Attempts to emulate GameCube memory card transfer speeds.

Wind Waker J has been tested and confirmed working with this by JMC47
Yes, when adding the wait for system blocks, the speeds are inconsistent and end up either being way longer than they are on gamecube, or shorter.