Enforce PROP_ONETIME on zpool properties

[behlendorf]

Description

Observed in #6277 that all one time props aren't being enforced by a generic check when verifying properties.

Motivation and Context

Enforce them, this is the @tuxoko's proposed fix from #6277 move in to it's own PR.

How Has This Been Tested?

Locally built.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the ZFS on Linux code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• All commit messages are properly formatted and contain Signed-off-by.
• Change has been approved by a ZFS on Linux member.

[codecov]

Codecov Report

Merging #7661 into master will increase coverage by 0.04%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #7661      +/-   ##
==========================================
+ Coverage   78.06%    78.1%   +0.04%     
==========================================
  Files         368      368              
  Lines      111627   111629       +2     
==========================================
+ Hits        87144    87192      +48     
+ Misses      24483    24437      -46

Flag	Coverage Δ
#kernel	78.73% <0%> (+0.06%)	⬆️
#user	67.01% <50%> (+0.28%)	⬆️

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