drm/crc-debugfs: Also sprinkle irqrestore over early exits

I. was. blind.

Caught with vkms, which has some really slow crc computation function.

Fixes: 1882018a ("drm/crc-debugfs: User irqsafe spinlock in drm_crtc_add_crc_entry")
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Emil Velikov <emil.velikov@collabora.com>
Cc: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190606211544.5389-1-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_debugfs_crc.c

@@ -402,7 +402,7 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
 
 	/* Caller may not have noticed yet that userspace has stopped reading */
 	if (!crc->entries) {
-		spin_unlock(&crc->lock);
+		spin_unlock_irqrestore(&crc->lock, flags);
 		return -EINVAL;
 	}
 
@@ -413,7 +413,7 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
 		bool was_overflow = crc->overflow;
 
 		crc->overflow = true;
-		spin_unlock(&crc->lock);
+		spin_unlock_irqrestore(&crc->lock, flags);
 
 		if (!was_overflow)
 			DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");