s390/facilities: remove stfle requirement

All call sites of "stfle" check if the instruction is available before
executing it. Therefore there is no reason to have the corresponding
facility bit set within the architecture level set.
This removes the last more or less odd bit from the list.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>