imx-drm mode fixup support, imx-hdmi bridge conversion and imx-drm cleanup

- Implement mode_fixup for a DI vertical timing limitation
- Use generic DRM OF helpers in DRM core
- Convert imx-hdmi to dw_hdmi drm_bridge and add rockchip
  driver
- Add DC use counter to fix multi-display support
- Simplify handling of DI clock flags
- A few small fixes and cleanup

* tag 'imx-drm-next-2015-01-09' of git://git.pengutronix.de/git/pza/linux: (26 commits)
  imx-drm: core: handling of DI clock flags to ipu_crtc_mode_set()
  gpu: ipu-di: Switch to DIV_ROUND_CLOSEST for DI clock divider calc
  gpu: ipu-v3: Use videomode in struct ipu_di_signal_cfg
  imx-drm: encoder prepare/mode_set must use adjusted mode
  imx-drm: ipuv3-crtc: Implement mode_fixup
  drm_modes: add drm_display_mode_to_videomode
  gpu: ipu-di: remove some non-functional code
  gpu: ipu-di: Add ipu_di_adjust_videomode()
  drm: rockchip: export functions needed by rockchip dw_hdmi bridge driver
  drm: bridge/dw_hdmi: request interrupt only after initializing the mutes
  drm: bridge/dw_hdmi: add rockchip rk3288 support
  dt-bindings: Add documentation for rockchip dw hdmi
  drm: bridge/dw_hdmi: add function dw_hdmi_phy_enable_spare
  drm: bridge/dw_hdmi: clear i2cmphy_stat0 reg in hdmi_phy_wait_i2c_done
  drm: bridge/dw_hdmi: add mode_valid support
  drm: bridge/dw_hdmi: add support for multi-byte register width access
  dt-bindings: add document for dw_hdmi
  drm: imx: imx-hdmi: move imx-hdmi to bridge/dw_hdmi
  drm: imx: imx-hdmi: split phy configuration to platform driver
  drm: imx: imx-hdmi: convert imx-hdmi to drm_bridge mode
  ...