drm/i915: Fix the TypeC port mode sanitization during loading/resume

drm/i915: Fix the TypeC port mode sanitization during loading/resume

For using the correct AUX power domains we have to sanitize the TypeC
port mode early, so move that before encoder sanitization. To do this
properly read out the actual port mode instead of just relying on the
VBT legacy port flag (which can be incorrect).

We also verify that the PHY is connected as expected if the port is
active. In case the port is inactive we connect the PHY in case of a
legacy port - as we did so far. The PHY will be connected during
detection for DP-alt mode - as it was done so far. For TBT-alt mode
nothing needs to be done to connect the PHY.

v2:
- Use DRM_DEBUG_KMS instead of DRM_DEBUG_DRIVER. (José)
v3:
- Detect TCCOLD any time PORT_TX_DFLEXDPCSSS is read. (Ville)

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190628143635.22066-14-imre.deak@intel.com