I/O stacks to PMON mapping on Skylake server relies on topology information
from CPU_BUS_NO MSR but this approach is not applicable for SNR and ICX.
Mapping on these platforms can be gotten by reading SAD_CONTROL_CFG CSR
from Mesh2IIO device with 0x09a2 DID.
SAD_CONTROL_CFG CSR contains stack IDs in its own notation which are
statically mapped on IDs in PMON notation.

The map for Snowridge:

Stack Name         | CBDMA/DMI | PCIe Gen 3 | DLB | NIS | QAT
SAD_CONTROL_CFG ID |     0     |      1     |  2  |  3  |  4
PMON ID            |     1     |      4     |  3  |  2  |  0

This patch enables I/O stacks to IIO PMON mapping on Snowridge.
Mapping is exposed through attributes /sys/devices/uncore_iio_<pmu_idx>/dieX,
where dieX is file which holds "Segment:Root Bus" for PCIe root port which
can be monitored by that IIO PMON block. Example for Snowridge:

==> /sys/devices/uncore_iio_0/die0 <==
0000:f3
==> /sys/devices/uncore_iio_1/die0 <==
0000:00
==> /sys/devices/uncore_iio_2/die0 <==
0000:eb
==> /sys/devices/uncore_iio_3/die0 <==
0000:e3
==> /sys/devices/uncore_iio_4/die0 <==
0000:14

Mapping for Icelake server will be enabled in the follow-up patch.
Signed-off-by: Alexander Antonov <alexander.antonov@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lkml.kernel.org/r/20210426131614.16205-3-alexander.antonov@linux.intel.com