sfc: Replace efx_rx_buffer::is_page and other booleans with a flags field

Replace checksummed and discard booleans from efx_handle_rx_event()
with a bitmask, added to the flags field.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index a352c55..952d0bf 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -229,8 +229,7 @@
 
 	/* Deliver last RX packet. */
 	if (channel->rx_pkt) {
-		__efx_rx_packet(channel, channel->rx_pkt,
-				channel->rx_pkt_csummed);
+		__efx_rx_packet(channel, channel->rx_pkt);
 		channel->rx_pkt = NULL;
 	}