PCI: rpaphp: Correctly match ibm, my-drc-index to drc-name when using drc-info

The newer ibm,drc-info property is a condensed description of the old
ibm,drc-* properties (ie. names, types, indexes, and power-domains).
When matching a drc-index to a drc-name we need to verify that the
index is within the start and last drc-index range and map it to a
drc-name using the drc-name-prefix and logical index.

Fix the mapping by checking that the index is within the range of the
current drc-info entry, and build the name from the drc-name-prefix
concatenated with the starting drc-name-suffix value and the sequential
index obtained by subtracting ibm,my-drc-index from this entries
drc-start-index.
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1573449697-5448-10-git-send-email-tyreld@linux.ibm.com

drivers/pci/hotplug/rpaphp_core.c

@@ -248,9 +248,10 @@ static int rpaphp_check_drc_props_v2(struct device_node *dn, char *drc_name,
 		/* Should now know end of current entry */
 
 		/* Found it */
-		if (my_index <= drc.last_drc_index) {
+		if (my_index >= drc.drc_index_start && my_index <= drc.last_drc_index) {
+			int index = my_index - drc.drc_index_start;
 			sprintf(cell_drc_name, "%s%d", drc.drc_name_prefix,
-				my_index);
+				drc.drc_name_suffix_start + index);
 			break;
 		}
 	}