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/pico-imx8mq_defconfig b/configs/pico-imx8mq_defconfig
index 86c3349..5b1dc81 100644
--- a/configs/pico-imx8mq_defconfig
+++ b/configs/pico-imx8mq_defconfig
@@ -11,7 +11,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="imx8mq-pico-pi"
 CONFIG_SPL_TEXT_BASE=0x7E1000
 CONFIG_TARGET_PICO_IMX8MQ=y
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL=y
 CONFIG_SYS_LOAD_ADDR=0x40480000
 CONFIG_FIT=y