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/ls1046ardb_qspi_spl_defconfig b/configs/ls1046ardb_qspi_spl_defconfig
index 1c2a1a1..349b991 100644
--- a/configs/ls1046ardb_qspi_spl_defconfig
+++ b/configs/ls1046ardb_qspi_spl_defconfig
@@ -18,7 +18,7 @@
 CONFIG_FSL_LS_PPA=y
 CONFIG_SPL_FSL_LS_PPA=y
 CONFIG_QSPI_AHB_INIT=y
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL_DRIVERS_MISC=y
 CONFIG_SPL=y
 CONFIG_AHCI=y