arm64: defconfig: Enable ARM SBSA watchdog driver

Enables ARM generic SBSA compatible watchdog driver for NXP LX2160a SoC.
Enabled as built-in for it is a core feature.
Signed-off-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm64/configs/defconfig

@@ -484,6 +484,7 @@ CONFIG_QCOM_SPMI_TEMP_ALARM=m
 CONFIG_UNIPHIER_THERMAL=y
 CONFIG_WATCHDOG=y
 CONFIG_ARM_SP805_WATCHDOG=y
+CONFIG_ARM_SBSA_WATCHDOG=y
 CONFIG_S3C2410_WATCHDOG=y
 CONFIG_DW_WATCHDOG=y
 CONFIG_SUNXI_WATCHDOG=m