On the Loongson64 platform, if CONFIG_SMP is not set, the following build
error will occur:
arch/mips/loongson64/reset.c:133:2: error:'secondary_kexec_args' undeclared

Because the definition and declaration of secondary_kexec_args are in the
CONFIG_SMP, the secondary_kexec_args variable should be used in CONFIG_SMP.
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NYouling Tang <tangyouling@loongson.cn>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NThomas Bogendoerfer <tsbogend@alpha.franken.de>