android: boot: content print is not supported for v3, v4 header version

android: boot: content print is not supported for v3, v4 header version

Content print is not supported for version 3 and 4 of boot image header.
Thus, only print that content when v2 is used.

Update android_print_contents() to print an error message
when trying to print boot image header version 3 or 4 content.

Signed-off-by: Safae Ouajih <souajih@baylibre.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>