habanalabs: allow unregistering eventfd when device non-operational

Unregistering eventfd is for releasing host resources and doesn't
involve an access to the device. As such, there is no reason to disallow
it when device isn't operational.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>