cxl/core/regs: Rework cxl_map_pmu_regs() to use map->dev for devm

cxl/core/regs: Rework cxl_map_pmu_regs() to use map->dev for devm

struct cxl_register_map carries a @dev parameter for devm operations.
Simplify the function interface to use that instead of a separate @dev
argument.

Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20231018171713.1883517-21-rrichter@amd.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>