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/wandboard_defconfig b/configs/wandboard_defconfig
index fa6e2b1..c1c069d 100644
--- a/configs/wandboard_defconfig
+++ b/configs/wandboard_defconfig
@@ -37,7 +37,7 @@
 CONFIG_SPL_FIT_IMAGE_TINY=y
 CONFIG_SPL_FS_EXT4=y
 CONFIG_SPL_I2C_SUPPORT=y
-CONFIG_SPL_WATCHDOG_SUPPORT=y
+CONFIG_SPL_WATCHDOG=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y