nfs: use %p[dD] instead of open-coded (and often racy) equivalents

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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

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

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

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

diff --cc fs/nfs/nfs3proc.c
Simple merge

diff --cc fs/nfs/nfs4file.c
Simple merge

diff --cc fs/nfs/nfs4namespace.c
Simple merge

diff --cc fs/nfs/nfs4proc.c
Simple merge

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

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

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