s390/facilities: remove extract-cpu-time facility check

Remove the check for the extract-cpu-time facility within early startup
code. Both kernel and user space work if the facility is not installed.

The vdso code has a run time check if the ectg is available. Besides that
there is no known user.

Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>