Save arguments as well as image name for CAS reboot

Save arguments as well as image name for CAS reboot

We were saving the image name that the user had typed (or had been
selected by default) in the "boot-last-label" property, but we were
losing any extra arguments that the user had typed after the image
name.  On a pSeries machine, if the firmware decides to do a reboot
at the client-architecture-support call, we were then rebooting to
the right image but without any extra arguments that the user typed.

This fixes the problem by saving the arguments in boot-last-label,
separated from the image name by a space.  When we use the value
of boot-last-label, we now call word_split to separate it into the
image name and arguments again.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>