cxl/port: Up-level cxl_add_dport() locking requirements to the caller

In preparation for moving dport enumeration into the core, require the
port device lock to be acquired by the caller.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164367759016.324231.105551648350470000.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/acpi.c

@@ -342,7 +342,9 @@ static int add_host_bridge_dport(struct device *match, void *arg)
 		return 0;
 	}
 
+	cxl_device_lock(&root_port->dev);
 	rc = cxl_add_dport(root_port, match, uid, ctx.chbcr);
+	cxl_device_unlock(&root_port->dev);
 	if (rc) {
 		dev_err(host, "failed to add downstream port: %s\n",
 			dev_name(match));