perf: CXL: fix mismatched number of counters mask

The number of Count Units field is described as 6 bits long
in the CXL 3.0 specification. However, its mask value was
only declared as 5 bits long.

Signed-off-by: Jeongtae Park <jtp.park@samsung.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20230905123309.775854-1-jtp.park@samsung.com


Signed-off-by: Will Deacon <will@kernel.org>