drm/i915: Gathering the HDCP1.4 routines together

All HDCP1.4 routines are gathered together, followed by the generic
functions those can be extended for HDCP2.2 too.

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1550338640-17470-2-git-send-email-ramalingam.c@intel.com