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/am64x_evm_r5_defconfig b/configs/am64x_evm_r5_defconfig
index b119c5b..6e68204 100644
--- a/configs/am64x_evm_r5_defconfig
+++ b/configs/am64x_evm_r5_defconfig
@@ -14,7 +14,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="k3-am642-r5-evm"
 CONFIG_SPL_TEXT_BASE=0x70000000
 CONFIG_SPL_MMC=y
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL_DRIVERS_MISC=y
 CONFIG_SPL_STACK_R_ADDR=0x82000000
 CONFIG_SPL_SIZE_LIMIT=0x190000