[pnfs] [0/10] draft-19 changes

[Dean Hildebrand]

These changes do some fixups and move layoutget/layoutcommit/
layoutreturn/getdeviceinfo/getdevicelist to draft 19.

They are on top of pnfs-d19.

We have tested these somewhat.  The I/O path works, but we
seem to have an unrelated gpfs issue that doesn't allow connectathon
to complete.  We thought it would be better to get them into
pnfs-d19 asap though as Andy and maybe others need to build
on top of them.

Notes:
a. The 128bit deviceid changed the NFSD export interface.
b. Patch 6 simplifies the layout driver callback device interface.

1. Fix cb_get_state
2. client 128bit deviceid 
3. server 128bit deviceid 
4. Client xdr for layoutget/layoutcommit/layoutreturn
5. Server xdr for layoutget/layoutcommit/layoutreturn
6. Cleanup of layout driver device callbacks. (for patch 7)
7. client getdeviceinfo
8. server getdeviceinfo
9. client getdevicelist
10. server getdevicelist