liquidio: Enhanced ethtool stats

1. Added red_drops stats. Inbound packets dropped by RED, buffer exhaustion
2. Included fcs_err, jabber_err, l2_err and frame_err errors under
   rx_errors
3. Included fifo_err, dmac_drop, red_drops, fw_err_pko, fw_err_link and
   fw_err_drop under rx_dropped
4. Included max_collision_fail, max_deferral_fail, total_collisions,
   fw_err_pko, fw_err_link, fw_err_drop and fw_err_pki under tx_dropped
5. Counting dma mapping errors
6. Added some firmware stats description and removed for some

Signed-off-by: Intiyaz Basha <intiyaz.basha@cavium.com>
Acked-by: Derek Chickles <derek.chickles@cavium.com>
Acked-by: Satanand Burla <satananda.burla@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>