gpg: Set default keysize to rsa3072
* g10/keygen.c (DEFAULT_STD_KEY_PARAM): Change. (gen_rsa): Set fallback to 3072. (get_keysize_range): Set default to 3072. * doc/examples/vsnfd.prf: No more need for default-new-key-algo.
- Signed-off-by: Werner Koch <wk@gnupg.org>