drm/i915: Align power domain names with port names

There is a difference in BSpec's and the driver's designation of DDI
ports. BSpec uses the following names:
- before GEN11:
  BSpec/driver:
  	port A/B/C/D etc
- GEN11:
  BSpec/driver:
	port A-F
- GEN12:
  BSpec:
  	port A/B/C for combo PHY ports
	port TC1-6 for Type C PHY ports
  driver:
	port A-I.
  The driver's port D name matches BSpec's TC1 port name.

So far power domains were named according to the BSpec designation, to
make it easier to match the code against the specification. That however
can be confusing when a power domain needs to be matched to a port on
GEN12+. To resolve that use the driver's port A-I designation for power
domain names too and rename the corresponding power wells so that they
reflect the mapping from the driver's to BSpec's port name.

Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190823100711.27833-1-imre.deak@intel.com