Currently, if the block device backing the IDE drive is resized,
the information about the device as cached inside of the IDEState
structure is not updated, thus when a guest OS re-queries the drive,
it is unable to see the expanded size.

This patch adds a resize callback that updates the IDENTIFY data
buffer in order to correct this.

Lastly, a Linux guest as-is cannot resize a libata drive while in-use,
but it can see the expanded size as part of a bus rescan event.
This patch also allows guests such as Linux to see the new drive size
after a soft reboot event, without having to exit the QEMU process.
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>