creating disks in update mode

[Matt_Domsch]

> > I did add a ops->new() function callback to allocate space
> > when ped_disk_new() is called, and fixed that in all the 
> other disk_xxx.c
> > files.
> 
> I don't want this.  I'll use update mode... so no partitions need to
> be created... but ped_disk_create() just needs to call
> _disk_pop_update_mode() after calling disk_type->ops->create().
> 
> (With update mode, we don't have free space or metadata partitions,
> so the problem disappears)

OK, I removed the new() function, added the call to _disk_pop_update_mode(),
removed 'static' from _disk_push_update_mode, and call that in
gpt_create() immediately after gpt_open() but before returning.

That seems to do the trick in 1.4.6. :)

Of course, I haven't fixed the other disk_xxx.c files yet.  I'm looking for
confirmation that I'm doing the right thing here.

Thanks,
Matt