rockchip: Fix rkimage format for SPL boot over USB

The 'rkimage' format used for booting rockchip boards over USB seems to
have been broken since commit 7bf274b9ca ("rockchip: mkimage: use
imagename to select spl hdr & spl size"). That commit adds an offset of
RK_SPL_HDR_START(=2048) to the location the 'RKxx' header is written
at. However the bootrom expects this header to be the first four bytes of
the image, not at offset 2048. This appears to have been a copy paste
error since the 'rksd' and 'rkspi' image types do require this offset.

Furthermore commit 111bcc4fb6 ("rockchip: mkimage: pad the header to
8-bytes (using a 'nop') for RK3399"), commit 3d54eabcaf ("rockchip:
spl: RK3399: use boot0 hook to create space for SPL magic") and
commit 3082775692 ("rockchip: mkimage: update rkimage to support
pre-padded payloads") changed the way the space for the 'RKxx' header is
allocated and written to the image without adjusting 'rkimage'.

This commit fixes those mistakes and makes it possible to load u-boot SPL
over USB once more.

(Tested on RK3399)

Signed-off-by: Daniel Gröber <daniel@dps.uibk.ac.at>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

tools/rkimage.c

@@ -15,8 +15,7 @@ static uint32_t header;
 static void rkimage_set_header(void *buf, struct stat *sbuf, int ifd,
 			       struct image_tool_params *params)
 {
-	memcpy(buf + RK_SPL_HDR_START, rkcommon_get_spl_hdr(params),
-	       RK_SPL_HDR_SIZE);
+	memcpy(buf, rkcommon_get_spl_hdr(params), RK_SPL_HDR_SIZE);
 
 	if (rkcommon_need_rc4_spl(params))
 		rkcommon_rc4_encode_spl(buf, 4, params->file_size);
@@ -36,7 +35,7 @@ static int rkimage_check_image_type(uint8_t type)
 U_BOOT_IMAGE_TYPE(
 	rkimage,
 	"Rockchip Boot Image support",
-	4,
+	0,
 	&header,
 	rkcommon_check_params,
 	NULL,