drm/edid: detect SCDC support in HF-VSDB

This patch does following:
- Adds a new structure (drm_hdmi_info) in drm_display_info.
  This structure will be used to save and indicate if sink
  supports advanced HDMI 2.0 features
- Adds another structure drm_scdc within drm_hdmi_info, to
  reflect scdc support and capabilities in connected HDMI 2.0 sink.
- Checks the HF-VSDB block for presence of SCDC, and marks it
  in scdc structure
- If SCDC is present, checks if sink is capable of generating
  SCDC read request, and marks it in scdc structure.

V2: Addressed review comments
  Thierry:
  - Fix typos in commit message and make abbreviation consistent
    across the commit message.
  - Change structure object name from hdmi_info -> hdmi
  - Fix typos and abbreviations in description of structure drm_hdmi_info
    end the description with a full stop.
  - Create a structure drm_scdc, and keep all information related to SCDC
    register set (supported, read request supported) etc in it.

  Ville:
  - Change rr -> read_request
  - Call drm_detect_scrambling function drm_parse_hf_vsdb so that all
    of HF-VSDB parsing can be kept in same function, in incremental
    patches.

V3: Rebase.
V4: Rebase.
V5: Rebase.
V6: Addressed review comments from Ville
  - Add clock rate calculations for 1/10 and 1/40 ratios
  - Remove leftovers from old patchset
V7: Added R-B from Jose.
V8: Rebase.
V9: Rebase.
V10: Rebase.

Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1489404244-16608-5-git-send-email-shashank.sharma@intel.com

include/drm/drm_connector.h

@@ -90,6 +90,20 @@ enum subpixel_order {
 
 };
 
+/**
+ * struct drm_scrambling: sink's scrambling support.
+ */
+struct drm_scrambling {
+	/**
+	 * @supported: scrambling supported for rates > 340 Mhz.
+	 */
+	bool supported;
+	/**
+	 * @low_rates: scrambling supported for rates <= 340 Mhz.
+	 */
+	bool low_rates;
+};
+
 /*
  * struct drm_scdc - Information about scdc capabilities of a HDMI 2.0 sink
  *
@@ -105,8 +119,13 @@ struct drm_scdc {
 	 * @read_request: sink is capable of generating scdc read request.
 	 */
 	bool read_request;
+	/**
+	 * @scrambling: sink's scrambling capabilities
+	 */
+	struct drm_scrambling scrambling;
 };
 
+
 /**
  * struct drm_hdmi_info - runtime information about the connected HDMI sink
  *