liquidio: fix VF driver off-by-one bug when setting ethtool -C ethX rx-frames

Signed-off-by: Weilin Chang <weilin.chang@cavium.com>
Signed-off-by: Derek Chickles <derek.chickles@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Weilin Chang

drivers/net/ethernet/cavium/liquidio/lio_ethtool.c

@@ -1808,7 +1808,7 @@ oct_cfg_rx_intrcnt(struct lio *lio,
 			    (octeon_read_csr64(
 				 oct, CN23XX_VF_SLI_OQ_PKT_INT_LEVELS(q_no)) &
 			     (0x3fffff00000000UL)) |
-				rx_max_coalesced_frames);
+				(rx_max_coalesced_frames - 1));
 			/*consider writing to resend bit here*/
 		}
 		intrmod->rx_frames = rx_max_coalesced_frames;