block: Add driver methods to probe blocksizes and geometry

Introduce driver methods of defining disk blocksizes (physical and
logical) and hard drive geometry.
Methods are only implemented for "host_device". For "raw" devices
driver calls child's method.

For now geometry detection will only work for DASD devices. To check
that a local check_for_dasd function was introduced. It calls BIODASDINFO2
ioctl and returns its rc.

Blocksizes detection function will probe sizes for DASD devices.

Signed-off-by: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1424087278-49393-4-git-send-email-tumanova@linux.vnet.ibm.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
