spl: Remove #ifdefs with BOOTSTAGE

This feature has some helpers in its header file so that its functions
resolve to nothing when the feature is disabled. Add a few more and use
these to simplify the code.

With this there are no more #ifdefs in board_init_r()

Signed-off-by: Simon Glass <sjg@chromium.org>

common/bootstage.c

@@ -502,6 +502,20 @@ int bootstage_unstash(const void *base, int size)
 	return 0;
 }
 
+int _bootstage_stash_default(void)
+{
+	return bootstage_stash(map_sysmem(CONFIG_BOOTSTAGE_STASH_ADDR, 0),
+			       CONFIG_BOOTSTAGE_STASH_SIZE);
+}
+
+int _bootstage_unstash_default(void)
+{
+	const void *stash = map_sysmem(CONFIG_BOOTSTAGE_STASH_ADDR,
+				       CONFIG_BOOTSTAGE_STASH_SIZE);
+
+	return bootstage_unstash(stash, CONFIG_BOOTSTAGE_STASH_SIZE);
+}
+
 int bootstage_get_size(void)
 {
 	struct bootstage_data *data = gd->bootstage;