Revert "ARM: mm: fix MMU mapping of CMA regions"

This reverts commit aa02c70b9f849e26798e65c399e9ea98f973524b.
Revert ARM: dma-mapping: add support for CMA regions placed in highmem zone
ARM: dma-mapping: Allow highmem pages to not have a mapping
Merge pull request #19 from crpalmer/cm-10.1-chad