consitify do_mount() arguments

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 651d845..24ab414 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2452,9 +2452,9 @@
 	return superblock_has_perm(cred, dentry->d_sb, FILESYSTEM__GETATTR, &ad);
 }
 
-static int selinux_mount(char *dev_name,
+static int selinux_mount(const char *dev_name,
 			 struct path *path,
-			 char *type,
+			 const char *type,
 			 unsigned long flags,
 			 void *data)
 {