fdt: Fix alignment issue when reading 64-bits properties from fdt

The FDT specification [0] gives a requirement of aligning properties on
32-bits. Make sure that the compiler is aware of this constraint when
accessing 64-bits properties.

[0]: https://github.com/devicetree-org/devicetree-specification/blob/master/source/flattened-format.rst

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/common/fdt_support.c b/common/fdt_support.c
index baf7924..6834399 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -1566,7 +1566,7 @@
 			 uint64_t *val, int cells)
 {
 	const fdt32_t *prop32 = &prop[cell_off];
-	const fdt64_t *prop64 = (const fdt64_t *)&prop[cell_off];
+	const unaligned_fdt64_t *prop64 = (const fdt64_t *)&prop[cell_off];
 
 	if ((cell_off + cells) > prop_len)
 		return -FDT_ERR_NOSPACE;