drm/i915: Name our BARs based on the spec

We use all kinds of weird names for our base address registers.
Take the names from the spec and stick to them to avoid confusing
everyone.

The only exceptions are IOBAR and LMEMBAR since naming them
IOBAR_BAR and LMEMBAR_BAR looks too funny, and yet I think
that adding the _BAR to GTTMMADR & co. (which don't have one
in the spec name) does make it more clear what they are.
And IOBAR vs. GTTMMADR_BAR also looks a bit too inconsistent
for my taste.

v2: Fix gvt build
v3: Add GEN2_IO_BAR for completeness

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221005195646.17201-1-ville.syrjala@linux.intel.com
Acked-by: Matthew Auld <matthew.auld@intel.com>

drm/i915: Extract intel_mmio_bar()

We have the same code to determine the MMIO BAR in
two places. Collect it to a single place.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221005154159.18750-1-ville.syrjala@linux.intel.com
Reviewed-by: Matthew Auld <matthew.auld@intel.com>

drm/i915: Use of BARs names instead of numbers

At the moment, when we refer to some PCI BAR we use the number of
this BAR in the code. The meaning of BARs between different platforms
may be different. Therefore, in order to organize the code,
let's start using defined names instead of numbers.

v2: Add lost header in cfg_space.c

Signed-off-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220805155959.1983584-2-piotr.piorkowski@intel.com

drm/i915: split out PCI config space registers from i915_reg.h

The PCI config space registers don't really belong next to the MMIO
register definitions.

v2: Fix copyright year (Matt)

Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220110095740.166078-1-jani.nikula@intel.com