hppfs pass vfsmount to dentry_open()

Here's patch for hppfs that uses vfs_kern_mount to make sure it always has a
procfs instance and passed the vfsmount on through the inode private data.
Also fixes a procfs file_system_type leak for every attempted hppfs mount.

[ jdike - gave this file a style workover, plus deleted hppfs_dentry_ops ]

Acked-by: Al Viro <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jeff Dike <[email protected]>
Signed-off-by: Dave Hansen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Al Viro <[email protected]>