nvme: fix possible hang when removing a controller during error recovery

Error recovery can be interrupted by controller removal, then the
controller is left as quiesced, and IO hang can be caused.

Fix the issue by unquiescing controller unconditionally when removing
namespaces.

This way is reasonable and safe given forward progress can be made
when removing namespaces.

Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reported-by: Chunguang Xu <brookxu.cn@gmail.com>
Closes: https://lore.kernel.org/linux-nvme/cover.1685350577.git.chunguang.xu@shopee.com/
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>