hw/cxl: Add CXL_CAPACITY_MULTIPLIER definition

hw/cxl: Add CXL_CAPACITY_MULTIPLIER definition

Remove usage of magic numbers when accessing capacity fields and replace
with CXL_CAPACITY_MULTIPLIER, matching the kernel definition.

Signed-off-by: Gregory Price <gregory.price@memverge.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20230206172816.8201-5-Jonathan.Cameron@huawei.com>
Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>