cpuidle: teo: Reorder candidate state index checks

Since constraint_idx may be 0, the candidate state index may change to 0
after assigning constraint_idx to it, so first check if it is greater
than constraint_idx (and update it if so) and then check it against 0.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/1907276.tdWV9SEqCh@rjwysocki.net