Some structures will be reused and shared between several IOS USB
device implementations. This prepares for the upcoming USB PR.
I've also removed GetPointer calls in the trivial case (BT passthrough)
IPC_HLE is actually IOS HLE. The actual IPC emulation is not in
IPC_HLE, but in HW/WII_IPC.cpp. So calling IPC_HLE IOS is more
accurate. (If IOS LLE gets ever implemented, it'll likely be at
a lower level -- Starlet LLE.)
This also totally gets rid of the IPC_HLE prefix in file names, and
moves some source files to their own subdirectories to make the file
hierarchy cleaner.
We're going to get ~14 additional source files with the USB PR,
and this is really needed to keep things from becoming a total pain.