netfilter: nftables: remove redundant assignment of variable err

The variable err is being assigned a value that is never read,
the same error number is being returned at the error return
path via label err1.  Clean up the code by removing the assignment.

Addresses-Coverity: ("Unused value")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_cmp.c

@@ -266,10 +266,8 @@ nft_cmp_select_ops(const struct nft_ctx *ctx, const struct nlattr * const tb[])
 	if (err < 0)
 		return ERR_PTR(err);
 
-	if (desc.type != NFT_DATA_VALUE) {
-		err = -EINVAL;
+	if (desc.type != NFT_DATA_VALUE)
 		goto err1;
-	}
 
 	if (desc.len <= sizeof(u32) && (op == NFT_CMP_EQ || op == NFT_CMP_NEQ))
 		return &nft_cmp_fast_ops;