MemMap: Fix Read32 for unaligned memory reads.

MemMap: Cleaned up Read32 unaligned memory access.
FS: Fix port name (old port name was based on an unaligned memory read).
MemMap: Removed Read64 function.

- Unused code
- Was not correct for unaligned memory reads
MemMap: Added an error for unaligned 16-bit memory reads.