drm/i915/lpe_audio: Remove pointless irq_to_desc() usage

Nothing uses the result and nothing should ever use it in driver code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20201210194043.862572239@linutronix.de

drivers/gpu/drm/i915/display/intel_lpe_audio.c

@@ -297,13 +297,9 @@ int intel_lpe_audio_init(struct drm_i915_private *dev_priv)
  */
 void intel_lpe_audio_teardown(struct drm_i915_private *dev_priv)
 {
-	struct irq_desc *desc;
-
 	if (!HAS_LPE_AUDIO(dev_priv))
 		return;
 
-	desc = irq_to_desc(dev_priv->lpe_audio.irq);
-
 	lpe_audio_platdev_destroy(dev_priv);
 
 	irq_free_desc(dev_priv->lpe_audio.irq);