rockchip: mkimage: add support for RK3308

Usage:

 (1) tools/mkimage -n rk3308 -T rksd -d tpl/u-boot-tpl.bin idbloader.img
 (2) cat spl/u-boot-spl.bin >> idbloader.img
 (3) upgrade_tool wl 0x40 idbloader.img

Note:
  When use ddr binary from rkbin as tpl, use it replace u-boot-tpl.bin in(1)
Signed-off-by: NAndy Yan <andy.yan@rock-chips.com>
Reviewed-by: NKever Yang <kever.yang@rock-chips.com>

tools/rkcommon.c

@@ -73,6 +73,7 @@ static struct spl_info spl_infos[] = {
 	{ "rk3188", "RK31", 0x8000 - 0x800, true },
 	{ "rk322x", "RK32", 0x8000 - 0x1000, false },
 	{ "rk3288", "RK32", 0x8000, false },
+	{ "rk3308", "RK33", 0x40000 - 0x1000, false},
 	{ "rk3328", "RK32", 0x8000 - 0x1000, false },
 	{ "rk3368", "RK33", 0x8000 - 0x1000, false },
 	{ "rk3399", "RK33", 0x30000 - 0x2000, false },