libfdisk: make it possible to reset device properties

libfdisk: make it possible to reset device properties

 - remember user C/H/S and sector size
 - reset all device properties before create a new label (maybe the
   old setting has been affected by previous on-disk label)
 - always apply user setting after the reset
 - improve topology/geometry debug messages

Note that for fdisk "user C/H/S and sector size" means on command line
specified values. If you override the setting by c/h/s commands in
expert menu then the setting is applied to the current disk label
only. If you create a new disk label (e.g change MBR to GPT) then
fdisk will use the original setting.

Signed-off-by: Karel Zak <kzak@redhat.com>