Fix wrong parameter of ssh-keygen

usage: ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile]
[-m format] [-N new_passphrase] [-O option]
[-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa]
[-w provider] [-Z cipher]

Reviewed at https://reviews.imfreedom.org/r/2418/