hw/cxl/cxl-mailbox-utils: Add mailbox commands to support add/release dynamic capacit...

hw/cxl/cxl-mailbox-utils: Add mailbox commands to support add/release dynamic capacity response

Per CXL spec 3.1, two mailbox commands are implemented:
Add Dynamic Capacity Response (Opcode 4802h) 8.2.9.9.9.3, and
Release Dynamic Capacity (Opcode 4803h) 8.2.9.9.9.4.

For the process of the above two commands, we use two-pass approach.
Pass 1: Check whether the input payload is valid or not; if not, skip
        Pass 2 and return mailbox process error.
Pass 2: Do the real work--add or release extents, respectively.

Tested-by: Svetly Todorov <svetly.todorov@memverge.com>
Reviewed-by: Gregory Price <gregory.price@memverge.com>
Signed-off-by: Fan Ni <fan.ni@samsung.com>
Message-Id: <20240523174651.1089554-11-nifan.cxl@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>