cxl/pci: Rename CXL REGLOC ID

The current naming is confusing and wrong. The Register Locator is
identified by the DSVSEC identifier, not an offset.

Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/20210618003009.956929-1-ben.widawsky@intel.com


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