extmod/network_cyw43: Fix uninitialised variable in status('stations').

[dpgeorge]

Summary

The num_stas was uninitialised and if it happened to take the value 0 then no results were returned. It now has the correct maximum value.

Testing

Tested with AP on PYBD_SF6 and two STA's connected (PYBD_SF2 and ESP32_GENERIC_S2). With the AP running the following code:

while True:
    print(ap.isconnected(), ap.status('stations'))
    time.sleep(1)

Prior to this fix ap.status('stations') would sometimes be empty. After the fix it always contained the correct MAC's.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.57%. Comparing base (f562aa1) to head (af743ea).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #16265   +/-   ##
=======================================
  Coverage   98.57%   98.57%           
=======================================
  Files         164      164           
  Lines       21347    21347           
=======================================
  Hits        21043    21043           
  Misses        304      304           

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[github-actions]

Code size report:

   bare-arm:    +0 +0.000% 
minimal x86:    +0 +0.000% 
   unix x64:    +0 +0.000% standard
      stm32:    +0 +0.000% PYBV10
     mimxrt:    +0 +0.000% TEENSY40
        rp2:   +24 +0.003% RPI_PICO_W
       samd:    +0 +0.000% ADAFRUIT_ITSYBITSY_M4_EXPRESS
  qemu rv32:    +0 +0.000% VIRT_RV32

[projectgus]

LGTM, one more to chalk up to automated testing! I'll send another PR to update the wlan test to call status('stations') and check the other ports.

It'd also be nice to #define MAC_LEN 6 at the top of this file and replace some of the other magic number 6s, but can do that in a follow-up as well.

[dpgeorge]

It'd also be nice to #define MAC_LEN 6 at the top of this file and replace some of the other magic number 6s, but can do that in a follow-up as well.

Yes, I agree. Also worth checking the other network drivers to see if they can have a similar improvement.