crypto: scompress - return proper error code for allocation failure

If scomp_acomp_comp_decomp() fails to allocate memory for the
destination then we never copy back the data we compressed.
It is probably best to return an error code instead 0 in case of
failure.
I haven't found any user that is using acomp_request_set_params()
without the `dst' buffer so there is probably no harm.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/scompress.c

@@ -171,9 +171,11 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
 	if (!ret) {
 		if (!req->dst) {
 			req->dst = sgl_alloc(req->dlen, GFP_ATOMIC, NULL);
-			if (!req->dst)
+			if (!req->dst) {
+				ret = -ENOMEM;
 				goto out;
 			}
+		}
 		scatterwalk_map_and_copy(scratch_dst, req->dst, 0, req->dlen,
 					 1);
 	}