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/arch/arm/mach-rmobile/Kconfig b/arch/arm/mach-rmobile/Kconfig
index 69e40cf..0e9c0fa 100644
--- a/arch/arm/mach-rmobile/Kconfig
+++ b/arch/arm/mach-rmobile/Kconfig
@@ -29,7 +29,7 @@
 	imply SPL_GZIP
 	imply SPL_LIBCOMMON_SUPPORT
 	imply SPL_LIBGENERIC_SUPPORT
-	imply SPL_SERIAL_SUPPORT
+	imply SPL_SERIAL
 	imply SPL_SYS_MALLOC_SIMPLE
 	imply SPL_TINY_MEMSET
 	imply SPL_YMODEM_SUPPORT