Signed-off-by: Michal Soltys <soltys@ziu.info>

disk_get_params():

Don't bail out if we fail int13h/48h call in ebios == 1 case. Regular
CHS might still be enough.

disk_read_sectors(), disk_write_sectors():

We don't need separate cases for valid and invalid cbios with the data
prepared by the current disk_get_params() function.

Signed-off-by: Michal Soltys <soltys@ziu.info>

With this commit, disk_info structure provides additional fields,
namely:

lbacnt - total amount of sectors, either returned by 13h/48h or calculated
from valid (or faked - 1/1/1) geometry

bps - bytes per sector - returned by 13h/48h or equal to SECTOR

disk_get_params() has been adjusted to call int13h/48h to get extended
drive parameters - mentioned lbacnt and bps. We don't use geometry
data returned by 13h/48h, as it can be quite a bit different from
the data returned by 13h/08h.

disk_write_verify_sector() and disk_write_sector() can deal with more
than 1 sector now. Suffix has been renamed to _sectors().

disk_read_sectors() and disk_write_sectors() have been updated to check
if we don't overflow bounce buffer, and don't try to read beyond lbacnt.

All disk.c functions use 'bps' now, instead of hardcoded SECTOR.

struct disk_ebios_dapa - uses packed attribute now.

Signed-off-by: Michal Soltys <soltys@ziu.info>

Functions disk_write_sector() and disk_write_verify_sector()
take 64bit lba as an argument now - similary to disk_read_sectors().

Structure disk_info additionally provides cylinders, besides head and sector.
Sanity checks during lba -> chs conversions have been adjusted to use
cylinders.

CX in cbios read/write code was not calculated properly.

Minor signed/unsigned changes.

Signed-off-by: Michal Soltys <soltys@ziu.info>