Revert "loop: Add sanity check for read/write_iter"

This reverts commit f5c84eff.

It causes CF to fail to boot, let's temporarily revert it until we find
a solution. Upstream has reported similar issues in [1] and [2] and
there is already a fix in the works. This can be brought back once such
fix lands upstream.

Bug: 417466278
Bug: 417627880
Change-Id: Ia361ec1c3ca0bca1391c0e9c56f77bf53c6bc2ab
Signed-off-by: Tudor Ambarus <tudordana@google.com>
Cc: Lucas Henneman <henneman@google.com>
Cc: Greg Kroah-Hartman <gregkh@google.com>
[cmllamas: restore from https://r.android.com/3622218 with a new
 Change-Id as the original revert got lost during a merge race, also add
 more information about the upstream reports.]
Link: https://bugs.debian.org/1106070 [1]
Link: https://lore.kernel.org/all/20250519175640.2fcac001@leda.eworm.net/

 [2]
Signed-off-by: Carlos Llamas <cmllamas@google.com>