afs: Make afs_zap_data() static

Make afs_zap_data() static as it's only used in the file in which it is
defined.
Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/inode.c

@@ -538,7 +538,7 @@ struct inode *afs_root_iget(struct super_block *sb, struct key *key)
  * mark the data attached to an inode as obsolete due to a write on the server
  * - might also want to ditch all the outstanding writes and dirty pages
  */
-void afs_zap_data(struct afs_vnode *vnode)
+static void afs_zap_data(struct afs_vnode *vnode)
 {
 	_enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
 

fs/afs/internal.h

@@ -1069,7 +1069,6 @@ extern int afs_ilookup5_test_by_fid(struct inode *, void *);
 extern struct inode *afs_iget_pseudo_dir(struct super_block *, bool);
 extern struct inode *afs_iget(struct afs_operation *, struct afs_vnode_param *);
 extern struct inode *afs_root_iget(struct super_block *, struct key *);
-extern void afs_zap_data(struct afs_vnode *);
 extern bool afs_check_validity(struct afs_vnode *);
 extern int afs_validate(struct afs_vnode *, struct key *);
 extern int afs_getattr(const struct path *, struct kstat *, u32, unsigned int);