io_uring/rsrc: fix incorrect assignment of iter->nr_segs in io_import_fixed

In io_import_fixed when advancing the iter within the first bvec, the
iter->nr_segs is set to bvec->bv_len. nr_segs should be the number of
bvecs, plus we don't need to adjust it here, so just remove it.

Fixes: b000ae0 ("io_uring/rsrc: optimise single entry advance")
Signed-off-by: Chenliang Li <cliang01.li@samsung.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20240619063819.2445-1-cliang01.li@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Chenliang Li

io_uring/rsrc.c

@@ -1068,7 +1068,6 @@ int io_import_fixed(int ddir, struct iov_iter *iter,
 			 * branch doesn't expect non PAGE_SIZE'd chunks.
 			 */
 			iter->bvec = bvec;
-			iter->nr_segs = bvec->bv_len;
 			iter->count -= offset;
 			iter->iov_offset = offset;
 		} else {