arm64: defconfig: enable sunxi watchdog

The SUNXI_WATCHDOG option is required to make the
watchdog available on Allwinner H6.

Enable this option as a module.
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

arch/arm64/configs/defconfig

@@ -420,6 +420,7 @@ CONFIG_UNIPHIER_THERMAL=y
 CONFIG_WATCHDOG=y
 CONFIG_ARM_SP805_WATCHDOG=y
 CONFIG_S3C2410_WATCHDOG=y
+CONFIG_SUNXI_WATCHDOG=m
 CONFIG_IMX2_WDT=y
 CONFIG_MESON_GXBB_WATCHDOG=m
 CONFIG_MESON_WATCHDOG=m