RAID5: check_reshape() shouldn't call mddev_suspend

RAID5: check_reshape() shouldn't call mddev_suspend

Orabug: 23331070

[ Upstream commit 27a353c026a879a1001e5eac4bda75b16262c44a ]

check_reshape() is called from raid5d thread. raid5d thread shouldn't
call mddev_suspend(), because mddev_suspend() waits for all IO finish
but IO is handled in raid5d thread, we could easily deadlock here.

This issue is introduced by
738a273 ("md/raid5: fix allocation of 'scribble' array.")

Cc: stable@vger.kernel.org (v4.1+)
Reported-and-tested-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 503f8305ab1b82d8788a2f161e7c52c0c0f6aeac)

Signed-off-by: Dan Duval <dan.duval@oracle.com>