drm/i915/hdcp: HDCP stream encryption support

drm/i915/hdcp: HDCP stream encryption support

Both HDCP_{1.x,2.x} requires to select/deselect Multistream HDCP bit
in TRANS_DDI_FUNC_CTL in order to enable/disable stream HDCP
encryption over DP MST Transport Link.

HDCP 1.4 stream encryption requires to validate the stream encryption
status in HDCP_STATUS_{TRANSCODER,PORT} register driving that link
in order to enable/disable the stream encryption.

Both of above requirement are same for all Gen with respect to
B.Spec Documentation.

v2:
- Cosmetic changes function name, error msg print and
  stream typo fixes. [Uma]
v3:
- uniformity for connector detail in DMESG. [Ram]

Cc: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ramalingam C <ramalingam.c@intel.com>
Tested-by: Karthik B S <karthik.b.s@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210111081120.28417-8-anshuman.gupta@intel.com