Allow encrypting data in FIT with binman

[Simon Glass]

Hi Paul,

Unfortunately I did not receive the email with your patch but I see it
in patchwork here:

https://patchwork.ozlabs.org/bundle/sjg/dm/?series=408037

I get this error:

binman test testSimpleFitEncryptedData
======================== Running binman tests ========================
E
======================================================================
ERROR: testSimpleFitEncryptedData (binman.ftest.TestFunctional)
Test an image with a FIT containing data to be encrypted
----------------------------------------------------------------------
ValueError: Error 1 running 'mkimage -t -k tools/binman/test -F
/tmp/binman.s_qv4_fc/fit.fit': File tools/binman/test/aes256.bin don't
have the expected size (size=0, expected=32)
mkimage Can't add hashes to FIT blob: -1
Error: Bad parameters for FIT image type
Usage: mkimage [-T type] -l image
...

The aes.bin file seems to be empty for me. Can you please check the patch?

Thank you for doing a proper test.  Can you also please update the
docs for Entry_fit to cover your new property, and regenerate
entries.rst ?

Note that there is a tools.readfile() helper which can read a binary/text file.

Regards,
Simon