exynos: Enable PSHOLD in SPL

There is quite a tight deadline in enabling PSHOLD, less than a second.
In some cases (e.g. with USB download), U-Boot takes longer than that
to load, so the board powers off before U-Boot starts.

Add a call in SPL to enable PSHOLD.
Signed-off-by: NSimon Glass <sjg@chromium.org>
Reviewed-by: NLukasz Majewski <l.majewski@samsung.com>
Signed-off-by: NMinkyu Kang <mk7.kang@samsung.com>

arch/arm/cpu/armv7/exynos/lowlevel_init.c

@@ -48,6 +48,8 @@ int do_lowlevel_init(void)
 
 	arch_cpu_init();
 
+	set_ps_hold_ctrl();
+
 	reset_status = get_reset_status();
 
 	switch (reset_status) {