consitify do_mount() arguments

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
(cherry picked from commit 808d4e3cfdcc52b19276175464f6dbca4df13b09)
diff --git a/security/security.c b/security/security.c
index cecd55e..0e1916e 100644
--- a/security/security.c
+++ b/security/security.c
@@ -280,8 +280,8 @@
 	return security_ops->sb_statfs(dentry);
 }
 
-int security_sb_mount(char *dev_name, struct path *path,
-                       char *type, unsigned long flags, void *data)
+int security_sb_mount(const char *dev_name, struct path *path,
+                       const char *type, unsigned long flags, void *data)
 {
 	return security_ops->sb_mount(dev_name, path, type, flags, data);
 }