drm/i915/pvc: Add register steering

drm/i915/pvc: Add register steering

Ponte Vecchio no longer has MSLICE or LNCF steering, but the bspec does
document several new types of multicast register ranges.  Fortunately,
most of the different MCR types all provide valid values at instance
(0,0) so there's no need to read fuse registers and calculate a
non-terminated instance.  We'll lump all of those range types (BSLICE,
HALFBSLICE, TILEPSMI, CC, and L3BANK) into a single category called
"INSTANCE0" to keep things simple.  We'll also perform explicit steering
for each of these multicast register types, even if the implicit
steering setup for COMPUTE/DSS ranges would have worked too; this is
based on guidance from our hardware architects who suggested that we
move away from implicit steering and start explicitly steer all MCR
register accesses on modern platforms (we'll work on transitioning
COMPUTE/DSS to explicit steering in the future).

Note that there's one additional MCR range type defined in the bspec
(SQIDI) that we don't handle here.  Those ranges use a different
steering control register that we never touch; since instance 0 is also
always a valid setting there, we can just ignore those ranges.

Finally, we'll rename the HAS_MSLICES() macro to HAS_MSLICE_STEERING().
PVC hardware still has units referred to as mslices, but there's no
register steering based on mslice for this platform.

v2:
 - Rebase on other recent changes
 - Swap two table rows to keep table sorted & easy to read.  (Harish)

Bspec: 67609
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Harish Chegondi <harish.chegondi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220608170700.4026648-1-matthew.d.roper@intel.com