MLK-24224-2 arm64: imx_v8_defconfig: select xen watchdog

Without this, domu will not able to use wdog function.

Reviewed-by: zhang sanshan <pete.zhang@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
(cherry picked from commit d60d1df)

arch/arm64/configs/imx_v8_defconfig

@@ -424,6 +424,7 @@ CONFIG_ARM_SBSA_WATCHDOG=y
 CONFIG_DW_WATCHDOG=y
 CONFIG_IMX2_WDT=y
 CONFIG_IMX_SC_WDT=y
+CONFIG_XEN_WDT=y
 CONFIG_MFD_BD9571MWV=y
 CONFIG_MFD_AXP20X_I2C=y
 CONFIG_MFD_IMX_AUDIOMIX=y