ARM: 7815/1: kexec: offline non panic CPUs on Kdump panic

In case of normal kexec kernel load, all cpu's are offlined
before calling machine_kexec().But in case crash panic cpus
are relaxed in machine_crash_nonpanic_core() SMP function
but not offlined.

When crash kernel is loaded with kexec and on panic trigger
machine_kexec() checks for number of cpus online.
If more than one cpu is online machine_kexec() fails to load
with below error

kexec: error: multiple CPUs still online

In machine_crash_nonpanic_core() SMP function, offline CPU
before cpu_relax

Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/machine_kexec.c

@@ -82,6 +82,7 @@ void machine_crash_nonpanic_core(void *unused)
 	crash_save_cpu(&regs, smp_processor_id());
 	flush_cache_all();
 
+	set_cpu_online(smp_processor_id(), false);
 	atomic_dec(&waiting_for_crash_ipi);
 	while (1)
 		cpu_relax();