[S390] smp: setup smp_processor_id early

smp_processor_id() is supposed to work before setup_arch() gets called.
Before that smp_processor_id() may return just an arbitrary value that
is contained in the uninitialized boot lowcore.
So provide the arch function which will override the weak function in
init/main.c.

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

arch/s390/kernel/setup.c

@@ -849,7 +849,6 @@ setup_arch(char **cmdline_p)
 	setup_lowcore();
 
         cpu_init();
-	__cpu_logical_map[0] = stap();
 	s390_init_cpu_topology();
 
 	/*