loop: don't clear LO_FLAGS_PARTSCAN on LOOP_SET_STATUS{,64}

loop: don't clear LO_FLAGS_PARTSCAN on LOOP_SET_STATUS{,64}

LOOP_SET_STATUS{,64} can set a lot more flags than it is supposed to
clear (the LOOP_SET_STATUS_CLEARABLE_FLAGS vs
LOOP_SET_STATUS_SETTABLE_FLAGS defines should have been a hint..).

Fix this by only clearing the bits in LOOP_SET_STATUS_CLEARABLE_FLAGS.

Fixes: ae074d07a0e5 ("loop: move updating lo_flag s out of loop_set_status_from_info")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250127143045.538279-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>