mkimage: rockchip: add suport for rk33 serial

Add support for rockchip rk33 series Soc like rk3368 and rk3399

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Simon Glass <sjg@chromium.org>

tools/rkcommon.c

@@ -56,6 +56,7 @@ struct spl_info {
 static struct spl_info spl_infos[] = {
 	{ "rk3036", "RK30", 0x1000 },
 	{ "rk3288", "RK32", 0x8000 },
+	{ "rk33xx", "RK33", 0x20000 },
 };
 
 static unsigned char rc4_key[16] = {