[U-Boot] [RFC PATCH 38/44] mkimage: Add -F option to modify an existing .fit file

[Marek Vasut]

Dear Simon Glass,

> When signing images it is sometimes necessary to sign with different keys
> at different times, or make the signer entirely separate from the FIT
> creation to avoid needing the private keys to be publicly available in
> the system.
> 
> Add a -F option so that key signing can be a separate step, and possibly
> done multiple times as different keys are avaiable.
> 
> Signed-off-by: Simon Glass <sjg at chromium.org>

Reviewed-by: Marek Vasut <marex at denx.de>

Best regards,
Marek Vasut