drm/fsl-dcu: enable IRQ before drm_atomic_helper_resume()

The resume helpers wait for a vblank to occurre hence IRQ need
to be enabled. This avoids a warning as follows during resume:
  WARNING: CPU: 0 PID: 314 at drivers/gpu/drm/drm_atomic_helper.c:1249 drm_atomic_helper_wait_for_vblanks.part.1+0x284/0x288
  [CRTC:28:crtc-0] vblank wait timed out
Signed-off-by: Stefan Agner <stefan@agner.ch>

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c

@@ -232,6 +232,7 @@ static int fsl_dcu_drm_pm_resume(struct device *dev)
 	if (fsl_dev->tcon)
 		fsl_tcon_bypass_enable(fsl_dev->tcon);
 	fsl_dcu_drm_init_planes(fsl_dev->drm);
+	enable_irq(fsl_dev->irq);
 	drm_atomic_helper_resume(fsl_dev->drm, fsl_dev->state);
 
 	console_lock();
@@ -239,7 +240,6 @@ static int fsl_dcu_drm_pm_resume(struct device *dev)
 	console_unlock();
 
 	drm_kms_helper_poll_enable(fsl_dev->drm);
-	enable_irq(fsl_dev->irq);
 
 	return 0;
 }