dmaengine: fsl-dpaa2-qdma: Drop comma after SoC match table sentinel

It does not make sense to have a comma after a sentinel, as any new
elements must be added before the sentinel.

Add a comment to clarify the purpose of the empty element.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/0b8ad4dcc185aa7a17655983e0eb5690d8fed460.1646311558.git.geert+renesas@glider.be
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: geertu

drivers/dma/fsl-dpaa2-qdma/dpaa2-qdma.h

@@ -139,7 +139,7 @@ struct dpaa2_qdma_priv_per_prio {
 
 static struct soc_device_attribute soc_fixup_tuning[] = {
 	{ .family = "QorIQ LX2160A"},
-	{ },
+	{ /* sentinel */ }
 };
 
 /* FD pool size: one FD + 3 Frame list + 2 source/destination descriptor */