bootstd: Avoid sprintf() in SPL when creating bootdevs

The name of the bootdev device is not that important, particular in SPL.
Save a little code space by using a simpler name.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/bootdev-uclass.c b/boot/bootdev-uclass.c
index 64ec4fd..2e61c85 100644
--- a/boot/bootdev-uclass.c
+++ b/boot/bootdev-uclass.c
@@ -16,6 +16,7 @@
 #include <malloc.h>
 #include <part.h>
 #include <sort.h>
+#include <spl.h>
 #include <dm/device-internal.h>
 #include <dm/lists.h>
 #include <dm/uclass-internal.h>
@@ -278,8 +279,13 @@
 	int ret, len;
 
 	len = bootdev_get_suffix_start(blk, ".blk");
-	snprintf(dev_name, sizeof(dev_name), "%.*s.%s", len, blk->name,
-		 "bootdev");
+	if (xpl_phase() < PHASE_BOARD_R) {
+		strlcpy(dev_name, blk->name, sizeof(dev_name) - 5);
+		strcat(dev_name, ".sib");
+	} else {
+		snprintf(dev_name, sizeof(dev_name), "%.*s.%s", len, blk->name,
+			 "bootdev");
+	}
 
 	parent = dev_get_parent(blk);
 	ret = device_find_child_by_name(parent, dev_name, &dev);