cpuidle: teo: Skip tick_nohz_get_sleep_length() call in some cases

Make teo_select() avoid calling tick_nohz_get_sleep_length() if the
candidate idle state to return is state 0 or if state 0 is a polling
one and the target residency of the current candidate one is below
a certain threshold, in which cases it may be assumed that the CPU will
be woken up immediately by a non-timer wakeup source and the timers
are not likely to matter.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Kajetan Puchalski <kajetan.puchalski@arm.com>
Tested-by: Anna-Maria Behnsen <anna-maria@linutronix.de>