s390/diag: Add busy-indication-facility requirements

To verify if busy indication facility is installed or not sclp bits has
to be checked. Add a function that checks sclp to improve readability.
Add busy-indication-request bit mask for diag204 subcodes.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Tobias Huschle <huschle@linux.ibm.com>
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>