perf/x86/intel/uncore: Add per-scheduler IMC CAS count events

IMC on SPR and EMR does not support sub-channels. In contrast, CPUs
that use gnr_uncores[] (e.g. Granite Rapids and Sierra Forest)
implement two command schedulers (SCH0/SCH1) per memory channel,
providing logically independent command and data paths.

Do not reuse the spr_uncore_imc[] configuration for these CPUs.
Instead, introduce a dedicated gnr_uncore_imc[] with per-scheduler
events, so userspace can monitor SCH0 and SCH1 independently.

On these CPUs, replace cas_count_{read,write} with
cas_count_{read,write}_sch{0,1}. This may break existing userspace
that relies on cas_count_{read,write}, prompting it to switch to the
per-scheduler events, as the legacy event reports only partial
traffic (SCH0).

Fixes: 632c4bf6d007 ("perf/x86/intel/uncore: Support Granite Rapids")
Fixes: cb4a6ccf3583 ("perf/x86/intel/uncore: Support Sierra Forest and Grand Ridge")
Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260210005225.20311-1-zide.chen@intel.com