The user recently report a perf issue in the ICX platform, when test by
perf event “uncore_imc_x/cas_count_write”,the write bandwidth is always
very small (only 0.38MB/s), it is caused by the wrong "umask" for the
"cas_count_write" event. When double-checking, find "cas_count_read"
also is wrong.

The public document for ICX uncore:

3rd Gen Intel® Xeon® Processor Scalable Family, Codename Ice Lake,Uncore
Performance Monitoring Reference Manual, Revision 1.00, May 2021

On 2.4.7, it defines Unit Masks for CAS_COUNT:
RD b00001111
WR b00110000

So corrected both "cas_count_read" and "cas_count_write" for ICX.

Old settings:
 hswep_uncore_imc_events
	INTEL_UNCORE_EVENT_DESC(cas_count_read,  "event=0x04,umask=0x03")
	INTEL_UNCORE_EVENT_DESC(cas_count_write, "event=0x04,umask=0x0c")

New settings:
 snr_uncore_imc_events
	INTEL_UNCORE_EVENT_DESC(cas_count_read,  "event=0x04,umask=0x0f")
	INTEL_UNCORE_EVENT_DESC(cas_count_write, "event=0x04,umask=0x30")

Fixes: 2b3b76b5 ("perf/x86/intel/uncore: Add Ice Lake server uncore support")
Signed-off-by: Zhengjun Xing <zhengjun.xing@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20211223144826.841267-1-zhengjun.xing@linux.intel.com