cxl: Add callback to parse the DSLBIS subtable from CDAT

cxl: Add callback to parse the DSLBIS subtable from CDAT

Provide a callback to parse the Device Scoped Latency and Bandwidth
Information Structure (DSLBIS) in the CDAT structures. The DSLBIS
contains the bandwidth and latency information that's tied to a DSMAS
handle. The driver will retrieve the read and write latency and
bandwidth associated with the DSMAS which is tied to a DPA range.

Coherent Device Attribute Table 1.03 2.1 Device Scoped Latency and
Bandwidth Information Structure (DSLBIS)

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/170319620005.2212653.7475488478229720542.stgit@djiang5-mobl3
Signed-off-by: Dan Williams <dan.j.williams@intel.com>