spi: sprd: adi: Add missing lock protection when rebooting

When rebooting the system, we should lock the watchdog after
configuration to make sure the watchdog can reboot the system
successfully.

Signed-off-by: Lingling Xu <ling_ling.xu@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Link: https://lore.kernel.org/r/7b04711127434555e3a1a86bc6be99860cd86668.1572257085.git.baolin.wang@linaro.org


Signed-off-by: Mark Brown <broonie@kernel.org>