Remove an old compatibility check/warning

It was IPv4-specific but nobody ever noticed this or reported the lack
of IPv6 check as a problem, suggesting that it is no longer needed.

pkg/proxy/iptables/proxier.go

@@ -91,7 +91,6 @@ const (
 )
 
 const sysctlRouteLocalnet = "net/ipv4/conf/all/route_localnet"
-const sysctlBridgeCallIPTables = "net/bridge/bridge-nf-call-iptables"
 const sysctlNFConntrackTCPBeLiberal = "net/netfilter/nf_conntrack_tcp_be_liberal"
 
 // internal struct for string service information
@@ -254,12 +253,6 @@ func NewProxier(ipFamily v1.IPFamily,
 		conntrackTCPLiberal = true
 		klog.InfoS("nf_conntrack_tcp_be_liberal set, not installing DROP rules for INVALID packets")
 	}
-	// Proxy needs br_netfilter and bridge-nf-call-iptables=1 when containers
-	// are connected to a Linux bridge (but not SDN bridges).  Until most
-	// plugins handle this, log when config is missing
-	if val, err := sysctl.GetSysctl(sysctlBridgeCallIPTables); err == nil && val != 1 {
-		klog.InfoS("Missing br-netfilter module or unset sysctl br-nf-call-iptables, proxy may not work as intended")
-	}
 
 	// Generate the masquerade mark to use for SNAT rules.
 	masqueradeValue := 1 << uint(masqueradeBit)