drm/i915/display/icl: HW state readout for transcoder port sync config

After the state is committed, we readout the HW registers and compare
the HW state with the SW state that we just committed.
For Transcdoer port sync, we add master_transcoder and the
salves bitmask to the crtc_state, hence we need to read those during
the HW state readout to avoid pipe state mismatch.

v11:
* Move master trans init to get pipe_Config hooks (Ville)
v10:
* Initialize master_tarnscoder readout for all platforms (Ville)
v9:
* Initialize master_transcoder = INVALID at get config (Ville)
v8:
* Use master_select -1, address TRANS_EDP case (Ville)
* Rename master_transcoder to _readout (Lucas)
v7:
* NDont read HW state for DSI
v6:
* Go through both parts of HW readout (Maarten)
* Add a WARN if the same trans configured as
master and slave (Ville, Maarten)
v5:
* Add return INVALID in defaut case (Maarten)
v4:
* Get power domains in master loop for get_config (Ville)
v3:
* Add TRANSCODER_D (Maarten)
* v3 Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
v2:
* Add Transcoder_D and MISSING_CASE (Maarten)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191018172725.1338-3-manasi.d.navare@intel.com