imx8qxp_mek: Remove SPL watchdog option

Currently the following watchdog error is seen in SPL:

U-Boot SPL 2020.04-00407-g8d5d3bcf3c (Apr 20 2020 - 09:48:09 -0300)
Normal Boot
WDT:   Not found!
...

There is no watchdog driver for i.MX8 at the moment, nor code for
configuring the watchdog in SPL, so remove the CONFIG_SPL_WATCHDOG_SUPPORT
option for now.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>
diff --git a/configs/imx8qxp_mek_defconfig b/configs/imx8qxp_mek_defconfig
index 8a7e9ee..e0f49f4 100644
--- a/configs/imx8qxp_mek_defconfig
+++ b/configs/imx8qxp_mek_defconfig
@@ -28,7 +28,6 @@
 CONFIG_SPL_SEPARATE_BSS=y
 CONFIG_SPL_POWER_SUPPORT=y
 CONFIG_SPL_POWER_DOMAIN=y
-CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_CPU=y
 # CONFIG_BOOTM_NETBSD is not set