crypto: algif_skcipher - Cap recv SG list at ctx->used

Somewhere along the line the cap on the SG list length for receive
was lost.  This patch restores it and removes the subsequent test
which is now redundant.

Fixes: 2d97591e ("crypto: af_alg - consolidation of...")
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/algif_skcipher.c

@@ -74,14 +74,10 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 		return PTR_ERR(areq);
 
 	/* convert iovecs of output buffers into RX SGL */
-	err = af_alg_get_rsgl(sk, msg, flags, areq, -1, &len);
+	err = af_alg_get_rsgl(sk, msg, flags, areq, ctx->used, &len);
 	if (err)
 		goto free;
 
-	/* Process only as much RX buffers for which we have TX data */
-	if (len > ctx->used)
-		len = ctx->used;
-
 	/*
 	 * If more buffers are to be expected to be processed, process only
 	 * full block size buffers.