ceph: remove redundant declaration

ceph_aops was already defined extern in addr.c section
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NYan, Zheng <zyan@redhat.com>

fs/ceph/super.h

@@ -882,7 +882,6 @@ extern int ceph_mmap(struct file *file, struct vm_area_struct *vma);
 
 /* file.c */
 extern const struct file_operations ceph_file_fops;
-extern const struct address_space_operations ceph_aops;
 
 extern int ceph_open(struct inode *inode, struct file *file);
 extern int ceph_atomic_open(struct inode *dir, struct dentry *dentry,