arm64: defconfig: add support for i.MX system controller watchdog

Enable CONFIG_IMX_SC_WDT as module to support i.MX system
controller watchdog.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/configs/defconfig

@@ -422,6 +422,7 @@ CONFIG_WATCHDOG=y
 CONFIG_ARM_SP805_WATCHDOG=y
 CONFIG_S3C2410_WATCHDOG=y
 CONFIG_IMX2_WDT=y
+CONFIG_IMX_SC_WDT=m
 CONFIG_MESON_GXBB_WATCHDOG=m
 CONFIG_MESON_WATCHDOG=m
 CONFIG_RENESAS_WDT=y