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/cm_fx6_defconfig b/configs/cm_fx6_defconfig
index 2ef935d..c110086 100644
--- a/configs/cm_fx6_defconfig
+++ b/configs/cm_fx6_defconfig
@@ -31,7 +31,7 @@
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0x80
 CONFIG_SPL_I2C_SUPPORT=y
 CONFIG_SPL_SPI_LOAD=y
-CONFIG_SPL_WATCHDOG_SUPPORT=y
+CONFIG_SPL_WATCHDOG=y
 CONFIG_SYS_PROMPT="CM-FX6 # "
 # CONFIG_CMD_XIMG is not set
 CONFIG_CMD_GREPENV=y