i40e: use minimal Rx and Tx ring buffers for kdump

Use the minimum of the number of descriptors thus we will allocate the
minimal ring buffers for kdump.

Signed-off-by: Coiby Xu <coxu@redhat.com>
Tested-by: Dave Switzer <david.switzer@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -11040,6 +11040,11 @@ static int i40e_set_num_rings_in_vsi(struct i40e_vsi *vsi)
 		return -ENODATA;
 	}
 
+	if (is_kdump_kernel()) {
+		vsi->num_tx_desc = I40E_MIN_NUM_DESCRIPTORS;
+		vsi->num_rx_desc = I40E_MIN_NUM_DESCRIPTORS;
+	}
+
 	return 0;
 }