dm-raid: only requeue bios when dm is suspending

dm-raid: only requeue bios when dm is suspending

Returning DM_MAPIO_REQUEUE from the target map() function only requeues
the bio during noflush suspends. During regular operations or during
flushing suspends, it fails the bio. Failing the bio during flushing
suspends is the correct behavior here. The bio cannot be handled, and
dm-raid cannot suspend while it is outstanding. But during normal
operations, dm-raid should not push the bio back to dm. Instead, wait
for the reshape to be resumed.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Reviewed-by: Xiao Ni <xiao@kernel.org>
Link: https://patch.msgid.link/20260428232010.2785514-1-bmarzins@redhat.com
Signed-off-by: Yu Kuai <yukuai@fygo.io>