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/T1024RDB_NAND_defconfig b/configs/T1024RDB_NAND_defconfig
index 1e44e62..82e79f0 100644
--- a/configs/T1024RDB_NAND_defconfig
+++ b/configs/T1024RDB_NAND_defconfig
@@ -9,7 +9,7 @@
 CONFIG_SYS_MALLOC_LEN=0xa00000
 CONFIG_DEFAULT_DEVICE_TREE="t1024rdb"
 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