clk/exynos4: Fix compilation warning

Fixes the following warning:
WARNING: drivers/built-in.o(.text.unlikely+0x2c50): Section mismatch in reference from the function exynos4_clk_sleep_init() to the (unknown reference) .init.data:(unknown)
   The function exynos4_clk_sleep_init() references
   the (unknown reference) __initdata (unknown).
   This is often because exynos4_clk_sleep_init lacks a __initdata
   annotation or the annotation of (unknown) is wrong.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

drivers/clk/samsung/clk-exynos4.c

@@ -324,7 +324,7 @@ static struct syscore_ops exynos4_clk_syscore_ops = {
 	.resume = exynos4_clk_resume,
 };
 
-static void exynos4_clk_sleep_init(void)
+static void __init exynos4_clk_sleep_init(void)
 {
 	exynos4_save_common = samsung_clk_alloc_reg_dump(exynos4_clk_regs,
 					ARRAY_SIZE(exynos4_clk_regs));
@@ -359,7 +359,7 @@ static void exynos4_clk_sleep_init(void)
 		__func__);
 }
 #else
-static void exynos4_clk_sleep_init(void) {}
+static void __init exynos4_clk_sleep_init(void) {}
 #endif
 
 /* list of all parent clock list */