s390/als: add vector facility to z13 architecture level set

Add the vector facility to the z13 architecture level set (ALS). All
hypervisors support the vector facility since many years.

Adding the facility to the ALS allows for compile time optimizations of the
kernel: if the kernel is compiled for z13 or later, all tests which verify
if the vector facility is present can return "true".
This will be implemented with a subsequent patch.

Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>