dmaengine: pxa/mmp: stop referencing config->slave_id

The last driver referencing the slave_id on Marvell PXA and MMP platforms
was the SPI driver, but this stopped doing so a long time ago, so the
TODO from the earlier patch can no be removed.

Fixes: b729bf34 ("spi/pxa2xx: Don't use slave_id of dma_slave_config")
Fixes: 13b3006b ("dma: mmp_pdma: add filter function")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211122222203.4103644-7-arnd@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/mmp_pdma.c

@@ -727,12 +727,6 @@ static int mmp_pdma_config_write(struct dma_chan *dchan,
 
 	chan->dir = direction;
 	chan->dev_addr = addr;
-	/* FIXME: drivers should be ported over to use the filter
-	 * function. Once that's done, the following two lines can
-	 * be removed.
-	 */
-	if (cfg->slave_id)
-		chan->drcmr = cfg->slave_id;
 
 	return 0;
 }

drivers/dma/pxa_dma.c

@@ -909,13 +909,6 @@ static void pxad_get_config(struct pxad_chan *chan,
 		*dcmd |= PXA_DCMD_BURST16;
 	else if (maxburst == 32)
 		*dcmd |= PXA_DCMD_BURST32;
-
-	/* FIXME: drivers should be ported over to use the filter
-	 * function. Once that's done, the following two lines can
-	 * be removed.
-	 */
-	if (chan->cfg.slave_id)
-		chan->drcmr = chan->cfg.slave_id;
 }
 
 static struct dma_async_tx_descriptor *