Missing totalRPs field when no RK are registered

[szszszsz]

If there are no RK registered on the device, then on credential listing attempt the device returns invalid CBOR structure, missing totalRPs field. The latter should always be shown, even when equal to 0.

Related: Nitrokey/pynitrokey#336 (comment)

nitrokey-fido2-firmware/fido2/ctap.c

Lines 1456 to 1462 in 12f2c14

	if (rp_count > 0)
	{
	ret = cbor_encode_int(&map, 5);
	check_ret(ret);
	ret = cbor_encode_int(&map, rp_count);
	check_ret(ret);
	}