exynos5420: Make the ps_hold_setup function public.

This function had been declared in a public header file, but was marked
static when actually defined.

Change-Id: Ia551a5a12e7dbaf7bc00861e085695145ab7b91a
Signed-off-by: Gabe Black <gabeblack@chromium.org>
Reviewed-on: http://review.coreboot.org/3657
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/cpu/samsung/exynos5420/power.c

@@ -24,9 +24,10 @@
 #include <arch/hlt.h>
 #include "cpu.h"
 #include "power.h"
+#include "setup.h"
 #include "sysreg.h"
 
-static void ps_hold_setup(void)
+void ps_hold_setup(void)
 {
 	struct exynos5_power *power =
 		samsung_get_base_power();