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/common/spl/spl.c b/common/spl/spl.c
index d55d3c2..2a9f54e 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -623,7 +623,7 @@
 		if (CONFIG_IS_ENABLED(SHOW_ERRORS))
 			ret = -ENXIO;
 		loader = spl_ll_find_loader(bootdev);
-		if (CONFIG_IS_ENABLED(SERIAL_SUPPORT) &&
+		if (CONFIG_IS_ENABLED(SERIAL) &&
 		    CONFIG_IS_ENABLED(LIBCOMMON_SUPPORT) &&
 		    !IS_ENABLED(CONFIG_SILENT_CONSOLE)) {
 			if (loader)
@@ -821,7 +821,7 @@
  */
 void preloader_console_init(void)
 {
-#ifdef CONFIG_SPL_SERIAL_SUPPORT
+#ifdef CONFIG_SPL_SERIAL
 	gd->baudrate = CONFIG_BAUDRATE;
 
 	serial_init();		/* serial communications setup */