rockchip: mkimage: Allow encoding of loader code in spl images

Rockchip SoCs allow the spl code to be rc4-encoded, not only the
image header, but only newer SoCs allow this encoding to be disabled.

The rk3188 is not part of those and requires its boot code to be
rc4-encoded with the regular key. So add the ability to do this
encoding via a setting on a per-soc basis when building spl images.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/tools/rkspi.c b/tools/rkspi.c
index a0b0051..0271d2e 100644
--- a/tools/rkspi.c
+++ b/tools/rkspi.c
@@ -48,6 +48,10 @@
 	memcpy(buf + RK_SPL_HDR_START, rkcommon_get_spl_hdr(params),
 	       RK_SPL_HDR_SIZE);
 
+	if (rkcommon_need_rc4_spl(params))
+		rkcommon_rc4_encode_spl(buf, RK_SPL_START - 4,
+					params->file_size - RK_SPL_START + 4);
+
 	/*
 	 * Spread the image out so we only use the first 2KB of each 4KB
 	 * region. This is a feature of the SPI format required by the Rockchip