Documentation/driver-api/cxl: device hotplug section

Documentation/driver-api/cxl: device hotplug section

Describe cxl memory device hotplug implications, in particular how the
platform CEDT CFMWS must be described to support successful hot-add of
memory devices.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Alejandro Lucero Palau <alucerop@amd.com>
Link: https://patch.msgid.link/20251219170538.1675743-3-gourry@gourry.net
Signed-off-by: Dave Jiang <dave.jiang@intel.com>