fix: Installation with mdraid mirroring with oem-resize and oem-systemsize set

[fnordic]

Fixes # Installation with mdraid mirroring with oem-resize and oem-systemsize set.

Changes proposed in this pull request:

do not device lock the not yet started $RaidDev:

Otherwise we observe in the boot.kiwi debug log:

...
+ declare kiwi_RaidDev=/dev/md0
+ set_device_lock /dev/md0 mdadm --assemble --scan /dev/md0 --update=devicesize
+ udevadm lock --help
+ udevadm lock --device /dev/md0 mdadm --assemble --scan /dev/md0 
Failed to find whole block device for '/dev/md0': No such file or directory
+ wait_for_storage_device /dev/md0
+ declare DEVICE_TIMEOUT=
+ local device=/dev/md
...

I removed the set_device_lock for raid activation.

set partition type to fd for raid:

Not strictly necessary:
If we do not enable oem-resize the partition type would be fd/raid and name p.lxraid as created by the kiwi/storage/disky.py.

assemble once after repart with devicesize update:

Otherwise the btrfs resize fails, because writing to raid device fails.
The mdadm --grow succeeds but if we look at the raid status afterwords in /proc/mdstat we observed:

Personalities : [raid1] 
md0 : broken raid1 sda4[0]
      2373568 blocks super 1.2 [2/1] [U_]

and with mdadm --examine for the underlying root partition, we still see the old partition size at "Avail Dev Size".
With an additional assemble the Avail Dev Size is reported correctly. Then the mdadm --grow actually resizes and is in state active and ready for the btrfs resize.

I added a new helper function update_devicesize_mdraid to assemble with --update=devicesize option and stop the array afterwards. The raid array is then ready for activation/resize.

[schaefi]

Great catch, thanks much 👍