net/mlx5: improve some comments

Replaced "its" with "it's".
Signed-off-by: Hu Haowen <xianfengting221@163.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/diag/fw_tracer.c

@@ -684,7 +684,7 @@ static void mlx5_fw_tracer_handle_traces(struct work_struct *work)
 		get_block_timestamp(tracer, &tmp_trace_block[TRACES_PER_BLOCK - 1]);
 
 	while (block_timestamp > tracer->last_timestamp) {
-		/* Check block override if its not the first block */
+		/* Check block override if it's not the first block */
 		if (!tracer->last_timestamp) {
 			u64 *ts_event;
 			/* To avoid block override be the HW in case of buffer