[POWERPC] Show state of spus as theyre stopped in Cell xmon helper

After stopping spus in xmon I often find myself trawling through the
field dumps to find out which spus were running. The spu stopping
code actually knows what's running, so let's print it out to save
the user some futzing.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>