s390/cpum_sf: Replace function name in debug statements

Replace hard coded function names in debug statements
by the "%s ...", __func__ construct suggested by checkpatch.pl
script.  Use consistent debug print format of the form variable
blank value. Also add leading 0x for all hex values.
Print allocated page addresses consistantly as hex numbers
with leading 0x.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>