[FREELDR]: More local changes merging, part 2/x:

[FREELDR]: More local changes merging, part 2/x:
- Move the HW detection code specific to the PC architecture from hardware.c to machpc.c, keeping in hardware.c the code that is shared between PC and XBOX.
- Move what remained of i386disk.c into pcdisk.c (specific to PC architecture) + code formatting.
- Move what remained of xboxhw.c into machxbox.c (specific to XBOX architecture); we discover that some code related to disk management is actually shared with PC architecture (in hwdisk.c): hwdisk.c therefore contains disk-management routines common to both PC & XBOX.
- xboxdisk.c: Code formatting only.
- Cleanup in disk.c/disk.h

svn path=/trunk/; revision=73616