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/porter_defconfig b/configs/porter_defconfig
index 358bed1..97b9e21 100644
--- a/configs/porter_defconfig
+++ b/configs/porter_defconfig
@@ -19,7 +19,7 @@
 CONFIG_ARCH_RMOBILE_BOARD_STRING="Porter"
 CONFIG_R8A7791=y
 CONFIG_TARGET_PORTER=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