arm64: kernel: add missing __init section marker to cpu_suspend_init

commit 18ab7db6 upstream.

Suspend init function must be marked as __init, since it is not needed
after the kernel has booted. This patch moves the cpu_suspend_init()
function to the __init section.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
[ luis: 3.16-stable prereq for
  f43c2718 "arm64: kernel: fix __cpu_suspend mm switch on warm-boot" ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

arch/arm64/kernel/suspend.c

@@ -119,7 +119,7 @@ int cpu_suspend(unsigned long arg)
 extern struct sleep_save_sp sleep_save_sp;
 extern phys_addr_t sleep_idmap_phys;
 
-static int cpu_suspend_init(void)
+static int __init cpu_suspend_init(void)
 {
 	void *ctx_ptr;