arm64: smp: make local symbol static

Make smp_spin_table_cpu_postboot() static, because this function
is used only in this file.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Git-commit: 7184659bed3090248e382d98a49a3c1bcfe11174
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>