Show device as journal in --detail --examine

Show device as journal in --detail --examine

Example output:

./mdadm --detail /dev/md127
/dev/md127:
        Version : 1.2
  Creation Time : Wed May 13 17:01:12 2015
     Raid Level : raid5
     Array Size : 11720662464 (11177.69 GiB 12001.96 GB)
  Used Dev Size : 3906887488 (3725.90 GiB 4000.65 GB)
   Raid Devices : 4
  Total Devices : 5
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Wed May 13 17:01:12 2015
          State : clean
 Active Devices : 4
Working Devices : 5
 Failed Devices : 0
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 32K

           Name : 0
           UUID : 8fb9ee05:3831d52f:e5c23825:28cd6881
         Events : 0

    Number   Major   Minor   RaidDevice State
       0       8       32        0      active sync   /dev/sdc
       1       8       48        1      active sync   /dev/sdd
       2       8       64        2      active sync   /dev/sde
       3       8       80        3      active sync   /dev/sdf

       4       8       17        -      journal   /dev/sdb1

./mdadm -E /dev/sdb2
/dev/sdb2:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x201
     Array UUID : 562b2334:35b9bcc1:add50892:1f30c4bd
           Name : 0
  Creation Time : Thu Aug 27 12:55:26 2015
     Raid Level : raid5
   Raid Devices : 15

 Avail Dev Size : 249796608 (119.11 GiB 127.90 GB)
     Array Size : 54696423936 (52162.57 GiB 56009.14 GB)
  Used Dev Size : 7813774848 (3725.90 GiB 4000.65 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262056 sectors, after=0 sectors
          State : active
    Device UUID : 5015e522:d39ba566:5909cf3c:9c51f2ff

Internal Bitmap : 8 sectors from superblock
    Update Time : Thu Aug 27 13:16:55 2015
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : 4e6fd76d - correct
         Events : 262

         Layout : left-symmetric
     Chunk Size : 256K

   Device Role : Journal
   Array State : AAAAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>