Adjust reiser4 to 3.16: ->{read,write}_iter of struct file_operations.

1. ->aio_{read,write} of struct file_operations are being replaced with ->{read,write}_iter.
2. do_sync_{read,write} are being replaced with new_sync_{read,write}.
3. generic_file_splice_write is being replaced with iter_file_splice_write.

Note that reiser4 somewhy doesn't work with generic_file_write_iter,
so we ditch ->splice_write instead of setting it to iter_file_splice_write.

Signed-off-by: Ivan Shapovalov <intelfx100@gmail.com>
Merge branch 'reiser4-3.14' into reiser4-3.16