idpf: fix handling rsc packet with a single segment

Handle rsc packet with a single segment same as a multi
segment rsc packet so that CHECKSUM_PARTIAL is set in the
skb->ip_summed field. The current code is passing CHECKSUM_NONE
resulting in TCP GRO layer doing checksum in SW and hiding the
issue. This will fail when using dmabufs as payload buffers as
skb frag would be unreadable.

Fixes: 3a8845af ("idpf: add RX splitq napi poll support")
Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Tested-by: Samuel Salin <Samuel.salin@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>