cxl/compliance: CXL Compliance Data Object Exchange implementation

The Data Object Exchange implementation of CXL Compliance Mode is
referring to "Compute Express Link (CXL) Specification, Rev. 2.0, Oct.
2020".

The data structure of CXL compliance request and response is added to
the header. Due to the scope limitation of QEMU, most of the compliance
response is limited to returning corresponding length.

A DOE capability of CXL Compliance is added to hw/mem/cxl_type3.c with
capability offset 0x160. The config read/write to this capability range
can be generated in the OS to request the Compliance info.

Signed-off-by: hchkuo <hchkuo@avery-design.com.tw>
Signed-off-by: Chris Browy <cbrowy@avery-design.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>