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/T2080QDS_SDCARD_defconfig b/configs/T2080QDS_SDCARD_defconfig
index 0097961..72ea4f8 100644
--- a/configs/T2080QDS_SDCARD_defconfig
+++ b/configs/T2080QDS_SDCARD_defconfig
@@ -8,7 +8,7 @@
 CONFIG_SPL_TEXT_BASE=0xFFFD8000
 CONFIG_FSL_USE_PCA9547_MUX=y
 CONFIG_SPL_MMC=y
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL_DRIVERS_MISC=y
 CONFIG_SPL=y
 CONFIG_MPC85xx=y