i915: Re-add DRM_I915_PREEMPT_TIMEOUT

Oops, this one is still used.

Author: evadot

include/drm/drm_bridge_connector.h

@@ -7,6 +7,7 @@ KCONFIG=	DRM_AMDGPU_CIK \
 		DRM_I915_CAPTURE_ERROR \
 		DRM_I915_USERFAULT_AUTOSUSPEND=250 \
 		DRM_I915_STOP_TIMEOUT=100 \
+		DRM_I915_PREEMPT_TIMEOUT=640 \
 		DRM_I915_HEARTBEAT_INTERVAL=2500 \
 		DRM_I915_TIMESLICE_DURATION=1 \
 		DRM_I915_MAX_REQUEST_BUSYWAIT=8000 \