ibmveth: Remove condition to recompute TCP header checksum.

ibmveth: Remove condition to recompute TCP header checksum.

In some OVS environments the TCP pseudo header checksum may need to be
recomputed. Currently this is only done when the interface instance is
configured for "Trunk Mode". We found the issue also occurs in some
Kubernetes environments, these environments do not use "Trunk Mode",
therefor the condition is removed.

Performance tests with this change show only a fractional decrease in
throughput (< 0.2%).

Fixes: 7525de2516fb ("ibmveth: Set CHECKSUM_PARTIAL if NULL TCP CSUM.")
Signed-off-by: David Wilder <dwilder@us.ibm.com>
Reviewed-by: Nick Child <nnac123@linux.ibm.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>