qstr: constify instances in hfs

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/hfs/trans.c b/fs/hfs/trans.c
index b1ce4c7..39f5e34 100644
--- a/fs/hfs/trans.c
+++ b/fs/hfs/trans.c
@@ -94,7 +94,7 @@
  * This routine is a inverse to hfs_mac2triv().
  * A ':' is replaced by a '/'.
  */
-void hfs_asc2mac(struct super_block *sb, struct hfs_name *out, struct qstr *in)
+void hfs_asc2mac(struct super_block *sb, struct hfs_name *out, const struct qstr *in)
 {
 	struct nls_table *nls_disk = HFS_SB(sb)->nls_disk;
 	struct nls_table *nls_io = HFS_SB(sb)->nls_io;