[Portstat] No data in output

[msosyak]

Description

Steps to reproduce the issue

1. portstat
2. portstat -c
3. portstat

Describe the results you received

admin@dut:~$ portstat
      IFACE    STATE    RX_OK    RX_BPS    RX_PPS    RX_UTIL    RX_ERR    RX_DRP    RX_OVR    TX_OK    TX_BPS    Tx_PPS    TX_UTIL    TX_ERR
-----------  -------  -------  --------  --------  ---------  --------  --------  --------  -------  --------  --------  ---------  --------
  Ethernet0        U     2986       N/A       N/A          0         0         0      2906      N/A       N/A         0          0         0
  Ethernet4        U     2907       N/A       N/A          0         0         0      2853      N/A       N/A         0          0         0
  Ethernet8        U     2888       N/A       N/A          0         0         0      2824      N/A       N/A         0          0         0
 Ethernet12        U     2976       N/A       N/A          0         0         0      2928      N/A       N/A         0          0         0
 Ethernet16        U     2932       N/A       N/A          0         0         0      2914      N/A       N/A         0          0         0

Describe the results you expected

Additional information you deem important (e.g. issue happens only occasionally)

Output of show version

(paste your output here)

[msosyak]

@mykolaf @yvolynets-mlnx @akokhan

[mykolaf]

@msosyak
See sonic-net/sonic-buildimage#2738