cmd: simplify command efidebug

cmd: simplify command efidebug

Currently we have subcommands 'efidebug dh' which shows protocols per
handle and 'efidebug devices' which shows the device path. None shows which
U-Boot device matches the handle.

Change 'efidebug dh' to show the device path and the U-Boot device if any
is associated with the handle.

Remove 'efidebug devices'.

Old output of 'efidebug dh':

    Handle           Protocols
    ================ ====================
    000000001b22e690 Device Path, Block IO
    000000001b22e800 Device Path, Block IO, system, Simple File System

New output of 'efidebug dh':

    000000001b22e690 (host0)
      /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/VenHw(bbe4e671-5773-4ea1-9aab-3a7dbf40c482,00)
      Block IO

    000000001b22e800 (host0:1)
      /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/VenHw(bbe4e671-5773-4ea1-9aab-3a7dbf40c482,00)/HD(1,GPT,7e5c17c5-3f5f-49d0-ae96-511b21d7f273,0x800,0x3f7df)
      Block IO
      system
      Simple File System

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>