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/display5_defconfig b/configs/display5_defconfig
index 53fe37c..06554b9 100644
--- a/configs/display5_defconfig
+++ b/configs/display5_defconfig
@@ -43,7 +43,7 @@
 CONFIG_SPL_I2C_SUPPORT=y
 CONFIG_SPL_OS_BOOT=y
 CONFIG_SPL_SPI_LOAD=y
-CONFIG_SPL_WATCHDOG_SUPPORT=y
+CONFIG_SPL_WATCHDOG=y
 CONFIG_HUSH_PARSER=y
 CONFIG_SYS_PROMPT="display5 > "
 CONFIG_CMD_BOOTZ=y