netlink: Issue #60, fix onewire not present, and hanging when it is.

[gsexton]

Fixes Issue #60, periph-cmd/onewire-list not working because the netlink package wasn't initialized.

There is a problem with loading netlink when the onewire bus drivers aren't loaded. If you run an executable with the netlink package loaded, and the onewire driver isn't loaded, the application hangs indefinitely. This was causing pipeline failures. It appears that netlink.Init() is sending a request on the netlink interface for onewire masters, but nothing is responding so it hangs.

My initial thought to resolve the hang was to put a network timeout on the request for onewire bus master. However, I think the approach of looking at the /sys/bus pseudo-filesystem is cleaner.

I'll follow up this PR with one to periph-cmd to do small fixes to onewire-list and add and ds18b20 program.

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 60.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 26.8%. Comparing base (b69b28c) to head (e05a20a).

Files with missing lines	Patch %	Lines
netlink/netlink_other.go	0.0%	2 Missing ⚠️
netlink/netlink_linux.go	80.0%	1 Missing ⚠️
netlink/onewire.go	66.7%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main     #61     +/-   ##
=======================================
+ Coverage   26.7%   26.8%   +0.1%     
=======================================
  Files         92      92             
  Lines      11538   11548     +10     
=======================================
+ Hits        3081    3097     +16     
+ Misses      8322    8316      -6     
  Partials     135     135             

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[maruel]

Thanks again!