[S390] Fix __ctl_load/__ctl_store inline assembly constraints

__ctl_load/__ctl_store are called with either an array of unsigned long or
a single unsigned long value. Add an address operator to the "m"/"=m"
contraints to make them work for unsigned long arguments as well.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>