vfs: switch ->show_options() to struct dentry *

Documentation/filesystems/Locking

Documentation/filesystems/vfs.txt

arch/s390/hypfs/inode.c

drivers/staging/pohmelfs/inode.c

drivers/usb/core/inode.c

fs/adfs/super.c

fs/autofs4/inode.c

fs/btrfs/super.c

fs/ceph/super.c

fs/cifs/cifsfs.c

fs/devpts/inode.c

fs/ecryptfs/super.c

fs/ext2/super.c

fs/ext3/super.c

fs/ext4/super.c

fs/fat/inode.c

fs/fuse/inode.c

fs/gfs2/super.c

fs/hfs/super.c

fs/hfsplus/hfsplus_fs.h