fw: use -malign-data=natural

Use -malign-data=natural; this makes structures align the way one
should have the right to expect.

riscv-opts.mk

@@ -3,7 +3,8 @@ riscv_target_flags =	-fvisibility=hidden \
 			-fno-pic -Wa,-fno-pic -fno-PIE \
 			-frename-registers -fshort-enums -fshort-wchar \
 			-ffunction-sections -fdata-sections \
-			-mshorten-memrefs -mstrict-align -fno-exceptions
+			-mshorten-memrefs -mstrict-align -fno-exceptions \
+			-malign-data=natural
 
 # Additional flags during application build
 riscv_flags = $(riscv_target_flags) \