Merge branch 'msm-fixes-3.12-rc2' of git://people.freedesktop.org/~robclark/linux into drm-fixes

A small fix + deal with fallout of iommu changes + use new
drm_gem_dumb_destroy helper.

* 'msm-fixes-3.12-rc2' of git://people.freedesktop.org/~robclark/linux:
  drm/msm: use drm_gem_dumb_destroy helper
  drm/msm: deal with mach/iommu.h removal
  drm/msm: Remove iommu include from mdp4_kms.c
  drm/msm: Odd PTR_ERR usage