intel_idle: Build fix

Because CONFIG_ soup.

Fixes: 6e1d2bc6 ("intel_idle: Fix intel_idle() vs tracing")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201130115402.GO3040@hirez.programming.kicks-ass.net