enforces Module imports granularity (#445)

src/ctap/mod.rs

@@ -75,11 +75,10 @@ use alloc::vec::Vec;
 use arrayref::array_ref;
 use byteorder::{BigEndian, ByteOrder};
 use core::convert::TryFrom;
-use crypto::ecdsa;
 use crypto::hmac::{hmac_256, verify_hmac_256};
 use crypto::rng256::Rng256;
 use crypto::sha256::Sha256;
-use crypto::Hash256;
+use crypto::{ecdsa, Hash256};
 use embedded_time::duration::Milliseconds;
 use sk_cbor as cbor;
 use sk_cbor::cbor_map_options;