net/i40e: fix multiple driver support

This patch provides the option to disable writing some global registers
in PMD, in order to avoid affecting other drivers, when multiple drivers
run on the same NIC and control different physical ports. Because there
are few global resources shared among different physical ports.

Fixes: ec246ee ("i40e: use default filter input set on init")
Fixes: 98f0557 ("i40e: configure input fields for RSS or flow director")
Fixes: f05ec7d ("i40e: initialize flow director flexible payload setting")
Fixes: e536c2e ("net/i40e: fix parsing QinQ packets type")
Fixes: 19b16e2 ("ethdev: add vlan type when setting ether type")
Cc: stable@dpdk.org

Signed-off-by: Beilei Xing <beilei.xing@intel.com>
Acked-by: Jingjing Wu <jingjing.wu@intel.com>