wiznet5k: Properly enable socket buffers for W5100(S).

[greezybacon]

The W5100 and W5100S only have 4 available sockets and 16kB of socket buffer. Allocating 16kB to either the receive or transmit buffer of a single socket is not allowed, so the current setup does not change the allocation for socket 0 from the reset default. ctlwizchip is returning -1 to indicate the error, but the response isn't being inspected and probably doesn't need to be.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.39%. Comparing base (63c30a2) to head (36ca2bf).

❗ Current head 36ca2bf differs from pull request most recent head 8762fe8. Consider uploading reports for the commit 8762fe8 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #14222      +/-   ##
==========================================
- Coverage   98.39%   98.39%   -0.01%     
==========================================
  Files         161      161              
  Lines       21204    21200       -4     
==========================================
- Hits        20864    20860       -4     
  Misses        340      340              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[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:    +0 +0.000% RPI_PICO
       samd:    +0 +0.000% ADAFRUIT_ITSYBITSY_M4_EXPRESS

[dpgeorge]

Thanks for the fix!