[S390] topology: export cpu topology via proc/sysinfo

Export the cpu configuration topology via sysinfo. Two new lines are
introduced:

CPU Topology HW:      0 0 0 4 6 4
CPU Topology SW:      0 0 0 0 4 24

The HW line describes the cpu topology nesting levels when the maximum
nesting level is used to get the corresponding SYSIB.
The SW line describes what Linux is actually using. In this case it
supports only two levels (CONFIG_SCHED_BOOK off) and therefore the
hardware folded the two lower levels in the SYSIB response block.

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