drm/i915: Wake device for emitting request during selftest

igt_mmap_offset_exhaustion() selftest was using live requests to make an
object busy, but we did not hold a runtime pm wakeref for submitting the
requests. Acquire it to avoid triggering "RPM wakelock ref not held
during HW access" warnings.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170411234427.14841-3-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/selftests/i915_gem_object.c

@@ -545,7 +545,9 @@ static int igt_mmap_offset_exhaustion(void *arg)
 		}
 
 		mutex_lock(&i915->drm.struct_mutex);
+		intel_runtime_pm_get(i915);
 		err = make_obj_busy(obj);
+		intel_runtime_pm_put(i915);
 		mutex_unlock(&i915->drm.struct_mutex);
 		if (err) {
 			pr_err("[loop %d] Failed to busy the object\n", loop);