net: ip6_gre: Remove generic .ndo_get_stats64

Commit 3e2f544dd8a33 ("net: get stats64 if device if driver is
configured") moved the callback to dev_get_tstats64() to net core, so,
unless the driver is doing some custom stats collection, it does not
need to set .ndo_get_stats64.

Since this driver is now relying in NETDEV_PCPU_STAT_TSTATS, then, it
doesn't need to set the dev_get_tstats64() generic .ndo_get_stats64
function pointer.

Signed-off-by: Breno Leitao <[e-mail]>
Reviewed-by: David Ahern <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv6/ip6_gre.c

···
 	.ndo_start_xmit		= ip6gre_tunnel_xmit,
 	.ndo_siocdevprivate	= ip6gre_tunnel_siocdevprivate,
 	.ndo_change_mtu		= ip6_tnl_change_mtu,
-	.ndo_get_stats64	= dev_get_tstats64,
 	.ndo_get_iflink		= ip6_tnl_get_iflink,
 };
 
···
 	.ndo_set_mac_address = eth_mac_addr,
 	.ndo_validate_addr = eth_validate_addr,
 	.ndo_change_mtu = ip6_tnl_change_mtu,
-	.ndo_get_stats64 = dev_get_tstats64,
 	.ndo_get_iflink = ip6_tnl_get_iflink,
 };
 
···
 	.ndo_set_mac_address =	eth_mac_addr,
 	.ndo_validate_addr =	eth_validate_addr,
 	.ndo_change_mtu =	ip6_tnl_change_mtu,
-	.ndo_get_stats64 =	dev_get_tstats64,
 	.ndo_get_iflink =	ip6_tnl_get_iflink,
 };