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/da850evm_defconfig b/configs/da850evm_defconfig
index 09a8f78..b65a8e6 100644
--- a/configs/da850evm_defconfig
+++ b/configs/da850evm_defconfig
@@ -17,7 +17,7 @@
 CONFIG_DM_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="da850-evm"
 CONFIG_SPL_TEXT_BASE=0x80000000
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL=y
 CONFIG_SPL_SPI_FLASH_SUPPORT=y
 CONFIG_SPL_SPI_SUPPORT=y