drm/i915/pmu: Remove !CONFIG_PM code

Chris spotted that since 16ffe73c18 ("drm/i915/pmu: Use GT parked for
estimating RC6 while asleep") we don't rely on runtime pm internals when
estimating RC6 while asleep. We can remove the ifdef code to simplify and
at the same time wake up the device less when querying RC6 if CONFIG_PM is
not compiled in.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
References: 16ffe73c18 ("drm/i915/pmu: Use GT parked for estimating RC6 while asleep")
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20201214094349.3563876-3-tvrtko.ursulin@linux.intel.com

drivers/gpu/drm/i915/i915_pmu.c

@@ -161,8 +161,6 @@ static u64 __get_rc6(struct intel_gt *gt)
 	return val;
 }
 
-#if IS_ENABLED(CONFIG_PM)
-
 static inline s64 ktime_since_raw(const ktime_t kt)
 {
 	return ktime_to_ns(ktime_sub(ktime_get_raw(), kt));
@@ -229,18 +227,6 @@ static void park_rc6(struct drm_i915_private *i915)
 	pmu->sleep_last = ktime_get_raw();
 }
 
-#else
-
-static u64 get_rc6(struct intel_gt *gt)
-{
-	return __get_rc6(gt);
-}
-
-static void init_rc6(struct i915_pmu *pmu) { }
-static void park_rc6(struct drm_i915_private *i915) {}
-
-#endif
-
 static void __i915_pmu_maybe_start_timer(struct i915_pmu *pmu)
 {
 	if (!pmu->timer_enabled && pmu_needs_timer(pmu, true)) {