NFSv4.1/pnfs: Refactor pnfs_set_layoutcommit()

pnfs_set_layoutcommit() and pnfs_commit_set_layoutcommit() are 100% identical
except for the function arguments. Refactor to eliminate the difference.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

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

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

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

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