key_management.c: if key is already in keyring don't report it as error
ecryptfs_add_passphrase_key_to_keyring gets return code 1 if key, it is trying to add to keyring, already exists in keyring. Return code remains 1, just don't report it as error.
Signed-off-by: Michal Hlavinka <mhlavink@redhat.com>