NFS: Revert pnfs ugliness from the generic NFS read code path

pNFS-specific code belongs in the pnfs layer. It should not be
hijacking generic NFS read or write code paths.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --cc fs/nfs/internal.h
Simple merge

diff --cc fs/nfs/pnfs.c
Simple merge

diff --cc fs/nfs/read.c
Simple merge