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: make ARM resemble the output of ARM_HYP preprocessing

The first step of merging the ARM hypervisor extensions into existing
ARM is to make the current ARM look like the preprocessed output of
ARM_HYP, which currently supports both platforms.

NOTE: this requires updates to ARM Refine and CRefine due to shuffling
around some constants (pteBits et al.). That is on its way.

haskell: move Haskell kernel into spec/