this patch provides little refactoring for the sys/boot/pc32/boot0 to improve
readability and comprehensibility of assembly code.
The main changes are:
Two new symbols added: _SECTOR_FIELD_OFF which provides offset for the 'sector'
field in CHS and _DATA_OFF which provides offset for the boot0 data from the
Some comments are improved
The patch was tested as in virtual machine as in real hardware (laptop ASUS M50).