core: Fix ERR_INV_ARG check in genkey_start
core: Fix ERR_INV_ARG check in genkey_start

* src/genkey.c (gpgme_op_genkey_start): Fix check for
parms.

--
This fixes a regression introduced by:
174af15725d4989a840ff3098996cc8a0568f724

So that the error was triggered by usual args.

GnuPG-Bug-Id: T4265

gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme,gpg/gpgme