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/ls1046aqds_nand_defconfig b/configs/ls1046aqds_nand_defconfig
index 431ea73..39a1e99 100644
--- a/configs/ls1046aqds_nand_defconfig
+++ b/configs/ls1046aqds_nand_defconfig
@@ -16,7 +16,7 @@
 CONFIG_SPL_TEXT_BASE=0x10000000
 CONFIG_FSL_USE_PCA9547_MUX=y
 CONFIG_FSL_LS_PPA=y
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL=y
 CONFIG_AHCI=y
 CONFIG_DISTRO_DEFAULTS=y