tools/mkimage: avoid a linux specific return code

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

SVN-Revision: 37368

tools/mkimage/patches/070-avoid_ENOMEDIUM.patch

@@ -0,0 +1,11 @@
+--- a/common/image-fit.c
++++ b/common/image-fit.c
+@@ -1557,7 +1557,7 @@ int fit_image_load(bootm_headers_t *imag
+ 	if (fit_image_get_data(fit, noffset, &buf, &size)) {
+ 		printf("Could not find %s subimage data!\n", prop_name);
+ 		bootstage_error(bootstage_id + BOOTSTAGE_SUB_GET_DATA);
+-		return -ENOMEDIUM;
++		return -EIO;
+ 	}
+ 	len = (ulong)size;
+