soc: fsl: dpio: Add prefetch instruction

In dpaa2_io_store_next(), if the current dequeue entry is not
the last, prefetch the next one as most likely it will be
requested shortly by the consumer driver.

This brings a ~3% improvement for dpaa2 ethernet driver
IP forwarding with small size frames.
Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Li Yang <leoyang.li@nxp.com>

drivers/soc/fsl/dpio/dpio-service.c

@@ -630,6 +630,7 @@ struct dpaa2_dq *dpaa2_io_store_next(struct dpaa2_io_store *s, int *is_last)
 		if (!(dpaa2_dq_flags(ret) & DPAA2_DQ_STAT_VALIDFRAME))
 			ret = NULL;
 	} else {
+		prefetch(&s->vaddr[s->idx]);
 		*is_last = 0;
 	}