cxl: Add checksum verification to CDAT from CXL

cxl: Add checksum verification to CDAT from CXL

A CDAT table is available from a CXL device. The table is read by the
driver and cached in software. With the CXL subsystem needing to parse the
CDAT table, the checksum should be verified. Add checksum verification
after the CDAT table is read from device.

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/169713682277.2205276.2687265961314933628.stgit@djiang5-mobl3
Signed-off-by: Dan Williams <dan.j.williams@intel.com>