gpioioctl: Fix an issue that would cause the GPIO chip handles to be closed by GC.

[gsexton]

Partially resolves:

periph/devices#105

Specifically, the Invalid File Descriptor error messages coming from GPIO.In() or GPIO.Out(). The issue was that when the impression driver did a big memory allocation, the GC was closing the file descriptors required for the GPIO system to work. The problem was that NewFile() DOES close file descriptors when the *os.File is garbage collected.

Minor tweak to close the unused (duplicate) chip rather than letting it leak or wait until GC'd.

This does not totally resolve devices #105. It's still not drawing.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.

Project coverage is 27.2%. Comparing base (02c216f) to head (b189df3).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
gpioioctl/gpio.go	0.0%	10 Missing ⚠️

❌ Your patch status has failed because the patch coverage (0.0%) is below the target coverage (60.0%). You can increase the patch coverage or adjust the target coverage.
❌ Your project status has failed because the head coverage (27.2%) is below the target coverage (60.0%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##            main     #68     +/-   ##
=======================================
- Coverage   27.2%   27.2%   -0.0%     
=======================================
  Files         96      96             
  Lines      11827   11834      +7     
=======================================
  Hits        3220    3220             
- Misses      8472    8479      +7     
  Partials     135     135             

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[maruel]

Thanks!