cmd/debos: Don't print command-line parsing error twice
cmd/debos: Don't print command-line parsing error twice

The command-line argument parsing library already prints any parsing
errors; there's no need to print the error again ourselves.

Signed-off-by: Christopher Obbard <0becaf7888cff31ba54e40b1ffb8263e09b8b7da@collabora.com>

go-debos/debos