zpool: fix conflict with -v and -o options

[Shreshth3]

Fixes #11040.

Right now, the -v and -o options for zpool list work independently, but when paired, the -v "wins out" and the -o effect is lost. This commit fixes that problem.

Before my change:

(master) ~/zfs$ ./zpool list -v -o name,health mypool
NAME          HEALTH
mypool        ONLINE
  mirror-0   960M   110K   960M        -         -     2%  0.01%      -    ONLINE
    loop17     1G      -      -        -         -      -      -      -    ONLINE
    loop18     1G      -      -        -         -      -      -      -    ONLINE

After my change:

(v-o-option-conflict) ~/zfs$ ./zpool list -v -o name,health mypool
NAME          HEALTH
mypool        ONLINE
  mirror-0    ONLINE
    loop17    ONLINE
    loop18    ONLINE

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)
• Quality assurance (non-breaking change which makes the code more robust against bugs)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.