drm/radeon/dp: return -EIO for flags not zero case

If there are error flags in the aux transaction return
-EIO rather than -EBUSY. -EIO restarts the whole transaction
while -EBUSY jus retries. Fixes problematic aux transfers.

Bug:
https://bugs.freedesktop.org/show_bug.cgi?id=80684

Signed-off-by: Alex Deucher <[e-mail]>
Cc: [e-mail]

drivers/gpu/drm/radeon/atombios_dp.c

···
 	/* flags not zero */
 	if (args.v1.ucReplyStatus == 2) {
 		DRM_DEBUG_KMS("dp_aux_ch flags not zero\n");
-		r = -EBUSY;
+		r = -EIO;
 		goto done;
 	}