haskell: explicitly import Prelude hiding Word

everywhere where it can clash with Word type defined by SEL4.

haskell: unify arm and arm-hyp haskell files

- both ARM and ARM_HYP haskell specs are now generated from the same set of files using cpp
- callbacks and platform files are merged into one directory (ARM)
- remove check-arm-hyp.py now that there are no ARM_HYP.lhs files

haskell: base arm-hyp off of arm-kzm