binman: btool: mkimage: use Bintool.version

Bintool.version already contains everything required to get the version
out of mkimage binary so let's not override it with its own
implementation.

Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed