serial: Rename SERIAL_SUPPORT to SERIAL

Rename these options so that CONFIG_IS_ENABLED can be used with them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/omapl138_lcdk_defconfig b/configs/omapl138_lcdk_defconfig
index 1316eaa..80e9023 100644
--- a/configs/omapl138_lcdk_defconfig
+++ b/configs/omapl138_lcdk_defconfig
@@ -19,7 +19,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="da850-lcdk"
 CONFIG_SPL_TEXT_BASE=0x80000000
 CONFIG_SPL_MMC=y
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL=y
 CONFIG_SYS_LOAD_ADDR=0xc0700000
 CONFIG_BOOTDELAY=3