defconfig: add NF_TABLES dependency for netlink_socket tests to pass

In order to support the NETFILTER_NETLINK protocol, either NF_TABLES or IP_SET must be enabled.
Neither are strict dependencies in Kconfig. Fix this by enabling NF_TABLES in the defconfig.

Before:
  ./netlinkcreate: socket(AF_NETLINK, SOCK_DGRAM, netfilter/12): Protocol not supported
  not ok 3
  # Test 3 got: "256" (./test at line 25)
  #   Expected: "0"
  #  ./test line 25 is: ok( $result, 0 );

After:
  ok 3

Signed-off-by: Alan Wandke <alanwandke.linux@gmail.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>

defconfig

@@ -55,6 +55,7 @@ CONFIG_IPV6_GRE=m
 CONFIG_SCSI_ISCSI_ATTRS=m
 CONFIG_NETFILTER_NETLINK=m
 CONFIG_CRYPTO_USER=m
+CONFIG_NF_TABLES=m
 
 # Overlay fs.
 # This is enabled to test overlayfs SELinux integration.