Rename SPL_WATCHDOG_SUPPORT to SPL_WATCHDOG

Rename this option so that CONFIG_IS_ENABLED can be used with it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/deneb_defconfig b/configs/deneb_defconfig
index 13c3587..25880dd 100644
--- a/configs/deneb_defconfig
+++ b/configs/deneb_defconfig
@@ -34,7 +34,7 @@
 CONFIG_SPL_SEPARATE_BSS=y
 CONFIG_SPL_POWER=y
 CONFIG_SPL_POWER_DOMAIN=y
-CONFIG_SPL_WATCHDOG_SUPPORT=y
+CONFIG_SPL_WATCHDOG=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="U-Boot# "
 CONFIG_CMD_CPU=y