block: Support providing LCHS from user

block: Support providing LCHS from user

Add logical geometry variables to BlockConf.

A user can now supply "lcyls", "lheads" & "lsecs" for any HD device
that supports CHS ("cyls", "heads", "secs").

These devices include:
    * ide-hd
    * scsi-hd
    * virtio-blk-pci

In future commits we will use the provided LCHS and pass it to the BIOS
through fw_cfg to be supplied using INT13 routines.

Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
Reviewed-by: Arbel Moshe <arbel.moshe@oracle.com>
Signed-off-by: Sam Eiderman <shmuel.eiderman@oracle.com>
Signed-off-by: Sam Eiderman <sameid@google.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>