fdt: Drop the confusing casts in lmb_free()

Just use map_to_sysmem() instead of all the casting.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/image-fdt.c b/boot/image-fdt.c
index 173ddb6..3e007d2 100644
--- a/boot/image-fdt.c
+++ b/boot/image-fdt.c
@@ -656,8 +656,7 @@
 
 	/* Delete the old LMB reservation */
 	if (lmb)
-		lmb_free(lmb, (phys_addr_t)(u32)(uintptr_t)blob,
-			 (phys_size_t)fdt_totalsize(blob));
+		lmb_free(lmb, map_to_sysmem(blob), fdt_totalsize(blob));
 
 	ret = fdt_shrink_to_minimum(blob, 0);
 	if (ret < 0)
@@ -666,7 +665,7 @@
 
 	/* Create a new LMB reservation */
 	if (lmb)
-		lmb_reserve(lmb, (ulong)blob, of_size);
+		lmb_reserve(lmb, map_to_sysmem(blob), of_size);
 
 	if (!ft_verify_fdt(blob))
 		goto err;