new helper: iov_iter_npages()

counts the pages covered by iov_iter, up to given limit.
do_block_direct_io() and fuse_iter_npages() switched to
it.

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

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

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

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

diff --cc mm/iov_iter.c
Simple merge