i40e: Initialize 64-bit statistics TX ring seqcount

On 32-bit hosts and with CONFIG_DEBUG_LOCK_ALLOC we should be seeing a
lockdep splat indicating this seqcount is not correctly initialized, fix
that.

Fixes: 980e9b11

 ("i40e: Add support for 64 bit netstats")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>