s390/cpum_cf: move counter set controls to a new header file

Move counter set specific controls and functions to the asm/cpu_mcf.h
header file containg all counter facility support definitions.  Also
adapt few variable names and header file includes.  No functional changes.

Signed-off-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>