[U-Boot] [PATCH v2] fdt: Fix mkimage list to try every header type

[sjg at google.com]

Image type is not supplied to `mkimage -l`. For this reason, we cannot
use imagetool_verify_print_header_by_type. Instead, this patch uses
imagetool_verify_print_header to look through all header types to find
one where image validation succeeds.

This patch fixes failures in test/image/test-imagetools.sh

Signed-off-by: Jordan Hand <jorhand at microsoft.com>
Tested-by: Alex Kiernan <alex.kiernan at gmail.com>
Tested-by: Vagrant Cascadian <vagrant at debian.org>
---

Changes in v2:
- Fix patch formatting to move commit message above the cut

 tools/mkimage.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

Applied to u-boot-dm, thanks!