ePass: Do not return positive exit code when the digest is not supported

The code paths for the ECDSA signatures provide SHA1 and SHA256 padding.
Any other padding should return an error as unsopported operation, but
given that the variable r was reused for some temporary calculation
it returned positive value, which was handled by the calling code as
a success.

Moreover, the calling code in use_key() function skipped the key operation
with this return value causing returning the uninitialized memory to the
calling process.

src/libopensc/card-epass2003.c

@@ -2204,6 +2204,7 @@ epass2003_set_security_env(struct sc_card *card, const sc_security_env_t * env,
 		}
 		else
 		{
+			r = SC_ERROR_NOT_SUPPORTED;
 			sc_log(card->ctx, "%0x Alg Not Support! ", env->algorithm_flags);
 			goto err;
 		}