f2fs: fix the f2fs_file_write_iter tracepoint

Pass in the original position and count rather than the position and
count that were updated by the write.  Also use the correct types for
all arguments, in particular the file offset which was being truncated
to 32 bits on 32-bit platforms.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>