Several lnetctl command usage strings in cmd_list[] were stale
and did not match the actual supported subcommands. A PR with the modifications below will follow this LU.

• Removed "help" from route, net, routing, stats, global, udsp,
  and fault usage strings, since "help" is not a subcommand
  handled by these jt_* functions and was misleading users.
• Added "reset" to the stats usage string, since jt_stats
  supports it but it was missing from the usage text.
• Added "show" to the udsp usage string, since jt_udsp supports
  it but it was missing from the usage text.