Align embedded device tree correctly

Device trees must be aligned to a 4-byte boundary. This was dropped in the
Kbuild conversion. Bring it back, and use 16-byte alignment for good
measure.

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

scripts/Makefile.lib

@@ -260,11 +260,13 @@ quiet_cmd_dt_S_dtb= DTB     $@
 cmd_dt_S_dtb=						\
 (							\
 	echo '.section .dtb.init.rodata,"a"';		\
+	echo '.balign 16';				\
 	echo '.global __dtb_$(*F)_begin';		\
 	echo '__dtb_$(*F)_begin:';			\
 	echo '.incbin "$<" ';				\
 	echo '__dtb_$(*F)_end:';			\
 	echo '.global __dtb_$(*F)_end';			\
+	echo '.balign 16';				\
 ) > $@
 
 $(obj)/%.dtb.S: $(obj)/%.dtb