switch iov_iter_get_pages() to passing maximal number of pages

... instead of maximal size.

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