i40e/i40evf: Fix i40e_rx_checksum

There are a couple of issues I found in i40e_rx_checksum while doing some
recent testing.  As a result I have found the Rx checksum logic is pretty
much broken and returning that the checksum is valid for tunnels in cases
where it is not.

First the inner types are not the correct values to use to test for if a
tunnel is present or not.  In addition the inner protocol types are not a
bitmask as such performing an OR of the values doesn't make sense.  I have
instead changed the code so that the inner protocol types are used to
determine if we report CHECKSUM_UNNECESSARY or not.  For anything that does
not end in UDP, TCP, or SCTP it doesn't make much sense to report a
checksum offload since it won't contain a checksum anyway.

This leaves us with the need to set the csum_level based on some value.
For that purpose I am using the tunnel_type field.  If the tunnel type is
GRENAT or greater then this means we have a GRE or UDP tunnel with an inner
header.  In the case of GRE or UDP we will have a possible checksum present
so for this reason it should be safe to set the csum_level to 1 to indicate
that we are reporting the state of the inner header.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>