drm/i915/tgl: Add power well support

The patch adds the new power wells introduced by TGL (GEN 12) and
maps these to existing/new power domains. The changes for GEN 12 wrt
to GEN 11 are the following:

- Transcoder#EDP removed from power well#1 (Transcoder#A used in
  low-power mode instead)
- Transcoder#A is now backed by power well#1 instead of power well#3
- The DDI#B/C combo PHY ports are now backed by power well#1 instead of
  power well#3
- New power well#5 added for pipe#D functionality (TODO)
- 2 additional TC ports (TC#5-6) backed by power well#3, 2 port
  specific IO power wells (only for the non-TBT modes) and 4 port
  specific AUX power wells (2-2 for TBT vs. non-TBT modes)
- Power well#2 backs now VDSC/joining for pipe#A instead of VDSC for
  eDP and MIPI DSI (TODO)

On TGL Port DDI#C changed to be a combo PHY (native DP/HDMI) and
BSpec has renamed ports DDI#D-F to TC#4-6 respectively. Thus on ICL we
have the following naming for ports:

- Combo PHYs (native DP/HDMI):
  DDI#A-B
- TBT/non-TBT (TC altmode, native DP/HDMI) PHYs:
  DDI#C-F

Starting from GEN 12 we have the following naming for ports:
- Combo PHYs (native DP/HDMI):
  DDI#A-C
- TBT/non-TBT (TC altmode, native DP/HDMI) PHYs:
  DDI TC#1-6

To save some space in the power domain enum the power domain naming in
the driver reflects the above change, that is power domains TC#1-3 are
added as aliases for DDI#D-F and new power domains are reserved for
TC#4-6.

v2 (Lucas):
  - Separate out the bits and definitions for TGL from the ICL ones.
    Fix use of TRANSCODER_EDP_VDSC, that is now the correct define since
    we don't define TRANSCODER_A_VDSC power domain to spare a one bit in
    the bitmask (suggested by Ville)
v3 (Lucas):
  - Fix missing squashes on v2
  - Rebase on renamed TRANSCODER_EDP_VDSC

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190711173115.28296-9-lucas.demarchi@intel.com