cdx: Unlock on error path in rescan_store()

We added locking to this function but these two error paths were
accidentally overlooked.

Fixes: f0af8168 ("cdx: Introduce lock to protect controller ops")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Acked-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Link: https://lore.kernel.org/r/a7994b47-6f78-4e2c-a30a-ee5995d428ec@moroto.mountain


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>