md: fix io loss when remove rdev fail

hulk inclusion
category: bugfix, https://gitee.com/openeuler/kernel/issues/I71EKW


bugzilla: 188628
CVE: NA

--------------------------------

We first set rdev to WantRemove, and check if there is any io
pending, if so, we will clear flag and return busy in
raid10_remove_disk(). io will loss as below:

  raid10_remove_disk
   set WantRemove
			write rdev
			 if WantRemove
			  do not submit io
   if rdev->nr_pending
    clear WantRemove
    return BUSY
					read rdev
					 get error data

Fix it by md_error the rdev which io pending while removing. When the code
reaches this point, it means this rdev will be removed later, so setting
it as faulty has little impact.

Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Hou Tao <houtao1@huawei.com>
(cherry picked from commit 894f89fa)