DM RAID: Clean-up handling of 'rebuild' device requests
dm-raid: Change the way the 'rebuild' parameter is processed.
1) We already allowed the rebuild flag to clear the superblock area for a
device. There is no reason to shame the user if they didn't clear the
superblock area ahead of time. Change the message to simply print-out
that it is clearing the superblock for the purpose of a rebuild.
2) Set the 'FirstUse' flag in 'super_load' vs 'super_init_validation'. This
allows the devices that had 'rebuild' set to be processed like a new device.
3) Since the rebuild devices are processed like new devices, the MD_CHANGE_DEVS
flag also gets set on the MD device. This was a necessary missing action
that forces the new superblock to be written when the array is instantiated.
Signed-off-by: Jonathan Brassow <firstname.lastname@example.org>