drm/radeon: Restore sw interrupt on resume

Fixes performance drop after suspend/resume on some systems.

Signed-off-by: Dave Airlie <[e-mail]>

drivers/char/drm/radeon_cp.c

···
 	radeon_cp_init_ring_buffer(dev, dev_priv);
 
 	radeon_do_engine_reset(dev);
+	radeon_enable_interrupt(dev);
 
 	DRM_DEBUG("radeon_do_resume_cp() complete\n");
 

drivers/char/drm/radeon_drv.h

···
 extern void radeon_driver_irq_preinstall(struct drm_device * dev);
 extern void radeon_driver_irq_postinstall(struct drm_device * dev);
 extern void radeon_driver_irq_uninstall(struct drm_device * dev);
+extern void radeon_enable_interrupt(struct drm_device *dev);
 extern int radeon_vblank_crtc_get(struct drm_device *dev);
 extern int radeon_vblank_crtc_set(struct drm_device *dev, int64_t value);
 

drivers/char/drm/radeon_irq.c

···
 	return radeon_wait_irq(dev, irqwait->irq_seq);
 }
 
-static void radeon_enable_interrupt(struct drm_device *dev)
+void radeon_enable_interrupt(struct drm_device *dev)
 {
 	drm_radeon_private_t *dev_priv = (drm_radeon_private_t *) dev->dev_private;