Revert "sna: Flush the batch before a render operation if the GPU is idle"

This reverts commit ad57ac07a2.

These checks end up being too frequent and not allowing us to batch
sufficient commands to offset the overhead of batch submission. Hmm.

src/sna/kgem.c

@@ -3578,9 +3578,6 @@ bool kgem_check_bo(struct kgem *kgem, ...)
 	DBG(("%s: num_pages=+%d, num_exec=+%d\n",
 	     __FUNCTION__, num_pages, num_exec));
 
-	if (kgem->nexec && kgem_is_idle(kgem))
-		return false;
-
 	if (!num_pages)
 		return true;