cxl: Split out combine_coordinates() for common shared usage

Refactor the common code of combining coordinates in order to reduce code.
Create a new function cxl_cooordinates_combine() it combine two 'struct
access_coordinate'.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20240308220055.2172956-6-dave.jiang@intel.com


Signed-off-by: Dan Williams <dan.j.williams@intel.com>