intel_hdcp_transcoder_config() is clobbering some globally visible
state in .compute_config(). That is a big no no as .compute_config()
is supposed to have no visible side effects when either the commit
fails or it's just a TEST_ONLY commit.

Inline this stuff into intel_hdcp_enable() so that the state only
gets modified when we actually commit the state to the hardware.

Cc: Ramalingam C <ramalingam.c@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Fixes: 39e2df09 ("drm/i915/hdcp: update current transcoder into intel_hdcp")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191204180549.1267-2-ville.syrjala@linux.intel.comReviewed-by: Ramalingam C <ramalingam.c@intel.com>