init: support owner/permission setting for sysfs attributes of devices

This should be much nicer than peppering init.rc with chown/chmod
directives.

Also, remove some dead code and obsolete comments.

Change-Id: I10895f10a9cf2f1226c8d12976cd3db3743da9ec
diff --git a/init/devices.h b/init/devices.h
index 8593a1b..a84fa58 100644
--- a/init/devices.h
+++ b/init/devices.h
@@ -21,7 +21,8 @@
 
 extern void handle_device_fd();
 extern void device_init(void);
-extern int add_dev_perms(const char *name, mode_t perm, unsigned int uid,
+extern int add_dev_perms(const char *name, const char *attr,
+                         mode_t perm, unsigned int uid,
                          unsigned int gid, unsigned short prefix);
 int get_device_fd();
 #endif	/* _INIT_DEVICES_H */