autoboot: Use if() for CONFIG_SILENT_CONSOLE

Avoid an #ifdef in this function, to improve readability.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/autoboot.c b/common/autoboot.c
index f832808..45df665 100644
--- a/common/autoboot.c
+++ b/common/autoboot.c
@@ -286,10 +286,8 @@
 	if (bootdelay >= 0)
 		abort = __abortboot(bootdelay);
 
-#ifdef CONFIG_SILENT_CONSOLE
-	if (abort)
+	if (IS_ENABLED(CONFIG_SILENT_CONSOLE) && abort)
 		gd->flags &= ~GD_FLG_SILENT;
-#endif
 
 	return abort;
 }