kpartx: Fixup find_unused_loop_device for sles11

On SLES11 the ioctl LOOP_CTL_GET_FREE isn't implemented, so
look into sysfs instead.

References: bnc#898427

Signed-off-by: Hannes Reinecke <hare@suse.de>
kpartx: use standard 'major' and 'minor' macros

Instead of hand-coding our own versions we should be using the
standard 'major' and 'minor' macros.
Otherwise higher minor numbers will not be referenced correctly.

References: bnc#898427

Signed-off-by: Hannes Reinecke <hare@suse.de>
- Update Changelog.