cmd/fat: Do not crash on write when <bytes> is not specified

argc is checked, but is off by one. In case <bytes> is not specified,
create an empty file, which is identical to the ext4write behaviour.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed