Fix remaining capacity handling of HP LTO6

[piste-jp]

Summary of changes

Fix how to get remaining capacity on HP LTO6.

• Fix of issue Formatting fails on HP LTO6 drive #241

Description

It looks HP LTO6 doesn't support LP17h. So this fix uses LP31h instead like IBM/HP LTO5.

Fixes #241

Type of change

Please delete items that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have confirmed my fix is effective or that my feature works