Some urgent regression fixes to booting failures Exynos DRM occured.

   Summary:
   - Fix two urgent null pointer dereference bugs in case of enabling
     or disabling IOMMU. There was two cases to these issues.
     One is that plane->crtc is accessed by exynos_disable_plane()
     when device tree binding is broken so device driver tries
     to release, which means that the mode set operation isn't invoked yet
     so plane->crtc is still NULL and exynos_disable_plane() will access
     NULL pointer. This issue is fixed by checking if the plane->crtc
     is NULL or not in exynos_disable_plane()

     Other is that fimd_wait_for_vblank() is called to avoid from page fault
     with IOMMU before the ctx object is created. At this time,
     fimd_wait_for_vblank() tries to access ctx->crtc but the ctx->crtc
     is still NULL because exynos_drm_crtc_create() isn't called yet.
     This issue is fixed by creating a crtc object and setting it to
     ctx->crtc prior to fimd_wait_for_vblank() call.

     For more details, you can refer to below an e-mail thread,
     http://www.spinics.net/lists/linux-samsung-soc/msg42436.html

   - Remove unnecessary file not used and fix trivial issues.

* 'exynos-drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos:
  drm/exynos: fix the initialization order in FIMD
  drm/exynos: fix typo config name correctly.
  drm/exynos: Check for NULL dereference of crtc
  drm/exynos: IS_ERR() vs NULL bug
  drm/exynos: remove unused files