ocxl: Use pci core's DVSEC functionality

ocxl: Use pci core's DVSEC functionality

Reduce maintenance burden of DVSEC query implementation by using the
centralized PCI core implementation.

There are two obvious places to simply drop in the new core
implementation. There remains find_dvsec_from_pos() which would benefit
from using a core implementation. As that change is less trivial it is
reserved for later.

Cc: linuxppc-dev@lists.ozlabs.org
Cc: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com> (v1)
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Link: https://lore.kernel.org/r/163379789065.692348.7117946955275586530.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>