netfilter: nft_socket: fix an unused variable warning

The variable is only used in an #ifdef, causing a harmless warning:

net/netfilter/nft_socket.c: In function 'nft_socket_init':
net/netfilter/nft_socket.c:137:27: error: unused variable 'level' [-Werror=unused-variable]
  137 |         unsigned int len, level;
      |                           ^~~~~

Move it into the same #ifdef block.

Fixes: e0bb96d ("netfilter: nft_socket: add support for cgroupsv2")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_socket.c

@@ -134,7 +134,7 @@ static int nft_socket_init(const struct nft_ctx *ctx,
 			   const struct nlattr * const tb[])
 {
 	struct nft_socket *priv = nft_expr_priv(expr);
-	unsigned int len, level;
+	unsigned int len;
 
 	if (!tb[NFTA_SOCKET_DREG] || !tb[NFTA_SOCKET_KEY])
 		return -EINVAL;
@@ -160,7 +160,9 @@ static int nft_socket_init(const struct nft_ctx *ctx,
 		len = sizeof(u32);
 		break;
 #ifdef CONFIG_CGROUPS
-	case NFT_SOCKET_CGROUPV2:
+	case NFT_SOCKET_CGROUPV2: {
+		unsigned int level;
+
 		if (!tb[NFTA_SOCKET_LEVEL])
 			return -EINVAL;
 
@@ -171,6 +173,7 @@ static int nft_socket_init(const struct nft_ctx *ctx,
 		priv->level = level;
 		len = sizeof(u64);
 		break;
+	}
 #endif
 	default:
 		return -EOPNOTSUPP;