dump-super: print something useful about zoned superblock

[kdave]

The zoned superblocks are different and current dump-super does not show anything different than for a regular filesystem. The first section of dump-super output is sort of a header, separate by dashes from the actual dump, so we can print the zone related information into the header section. What could be useful:

• zone size
• real physical offset of the latest superblock
• which zone is it? there are always 2 zones covering a single super block
• add a new option to print the whole super block log? or a specific one (with special value to print all)