pnfs: clean up *_resend_to_mds

Clean up pnfs_read_done_resend_to_mds and pnfs_write_done_resend_to_mds:
 - instead of passing all arguments from a nfs_pgio_header, just pass the header
 - share the common code

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

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

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

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

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

diff --cc include/linux/nfs_page.h
Simple merge