s390/topology: fix compile error in file arch/s390/kernel/smp.c

Commit 1887aa07
("s390/topology: add detection of dedicated vs shared CPUs")
introduced following compiler error when CONFIG_SCHED_TOPOLOGY is not set.

 CC      arch/s390/kernel/smp.o
...
arch/s390/kernel/smp.c: In function ‘smp_start_secondary’:
arch/s390/kernel/smp.c:812:6: error: implicit declaration of function
	‘topology_cpu_dedicated’; did you mean ‘topology_cpu_init’?

This patch fixes the compiler error by adding function
topology_cpu_dedicated() to return false when this config option is
not defined.

Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>