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/lager_defconfig b/configs/lager_defconfig
index 91f9fe6..7c6e05c 100644
--- a/configs/lager_defconfig
+++ b/configs/lager_defconfig
@@ -19,7 +19,7 @@
 CONFIG_ARCH_RMOBILE_BOARD_STRING="Lager"
 CONFIG_R8A7790=y
 CONFIG_TARGET_LAGER=y
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL_SYS_MALLOC_F_LEN=0x2000
 CONFIG_SPL=y
 CONFIG_SPL_SPI_FLASH_SUPPORT=y