net/mrvl: fix shadow queue tail and size calculations

Reset skip_buf after use to avoid wrong tail and size calculations.

Fixes: afb4d0d0bf91 ("net/mrvl: add Rx/Tx support")
Cc: stable@dpdk.org

Signed-off-by: Natalie Samsonov <nsamsono@marvell.com>

drivers/net/mrvl/mrvl_ethdev.c

@@ -1932,6 +1932,7 @@ skip:
 		sq->tail = (sq->tail + num) & MRVL_PP2_TX_SHADOWQ_MASK;
 		sq->size -= num;
 		num = 0;
+		skip_bufs = 0;
 	}
 
 	if (likely(num)) {