Improve save_boot_device and restore_boot_device snippets

Make sure that boot order is saved/restored for Suse and Red Hat-based
distributions on Power architecture. This worked only in Fedora 17
and SLES 11 before and it was not default behavior.

Signed-off-by: Nathan Ozelim <natoze@linux.vnet.ibm.com>
Merge pull request #715 from alanoe/alanoe/restore_boot_order

Improve save_boot_device and restore_boot_device snippets