drm/i915: header for i915 - MEI_HDCP interface

drm/i915: header for i915 - MEI_HDCP interface

Header defines the interface for the I915 and MEI_HDCP drivers.
This interface is specific to the usage of mei_hdcp from gen9+
platforms for ME FW based HDCP2.2 services.

And Generic HDCP2.2 protocol specific definitions
are added at drm/drm_hdcp.h.

v2:
  Commit msg is enhanced [Daniel]
v3:
  i915_hdcp_comp_master is defined.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> [v2]
Reviewed-by: Uma Shankar <uma.shankar@intel.com> [v2]
[danvet: Fix subject to drm/i915.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1550219730-17734-4-git-send-email-ramalingam.c@intel.com