align spelling of “RAID” and RAID levels

* Aligned the spelling of “RAID” to use captial letters in all places.
* Aligned the spelling of the RAID level names (LINEAR, RAID1, …) to use capital
  letters in all places, except for the string “faulty” in places where not the
  RAID level was meant.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
align spelling of “MD”

* Aligned the spelling of “MD”  to use capital letters in all places where the
system/driver is meant.

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>