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/edminiv2_defconfig b/configs/edminiv2_defconfig
index c5890e2..e74f4db 100644
--- a/configs/edminiv2_defconfig
+++ b/configs/edminiv2_defconfig
@@ -11,7 +11,7 @@
 CONFIG_SYS_MALLOC_LEN=0x40000
 CONFIG_SPL_TEXT_BASE=0xffff0000
 CONFIG_TARGET_EDMINIV2=y
-CONFIG_SPL_SERIAL_SUPPORT=y
+CONFIG_SPL_SERIAL=y
 CONFIG_SPL=y
 CONFIG_IDENT_STRING=" EDMiniV2"
 CONFIG_SYS_LOAD_ADDR=0x800000