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/T2080RDB_revD_NAND_defconfig b/configs/T2080RDB_revD_NAND_defconfig
index 41528bd..4b087a8 100644
--- a/configs/T2080RDB_revD_NAND_defconfig
+++ b/configs/T2080RDB_revD_NAND_defconfig
@@ -8,7 +8,7 @@
 CONFIG_ENV_OFFSET=0x100000
 CONFIG_DEFAULT_DEVICE_TREE="t2080rdb"
 CONFIG_SPL_TEXT_BASE=0xFFFD8000
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL_DRIVERS_MISC=y
 CONFIG_SPL=y
 CONFIG_MPC85xx=y