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 <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>