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 <[e-mail]>
Signed-off-by: Catalin Marinas <[e-mail]>

arch/arm64/kernel/smp_spin_table.c

···
 	return secondary_holding_pen_release != INVALID_HWID ? -ENOSYS : 0;
 }
 
-void smp_spin_table_cpu_postboot(void)
+static void smp_spin_table_cpu_postboot(void)
 {
 	/*
 	 * Let the primary processor know we're out of the pen.