zdev: Introduce the ap device type

The AP device type initially allows only the setting of type
attributes 'apmask' and 'aqmask'.

Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/src/path.c

@@ -398,3 +398,9 @@ char *path_get_scsi_hctl_dev(const char *hctl)
 {
 	return path_get("/sys/bus/scsi/devices/%s", hctl);
 }
+
+/* Return sysfs path to a bus attribute */
+char *path_get_bus_attr(const char *bus, const char *attr)
+{
+	return path_get("/sys/bus/%s/%s", bus, attr);
+}