dmaengine: imx-sdma: remove dummy assignment

David reported:
drivers/dma/imx-sdma.c:1003]: (style) Same expression on both sides of '|='

ORing with itself yields same result, So remove this

Reported-by: David Binderman <dcb314@hotmail.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/imx-sdma.c

@@ -993,8 +993,6 @@ static int sdma_config_channel(struct dma_chan *chan)
 		} else
 			__set_bit(sdmac->event_id0, sdmac->event_mask);
 
-		/* Watermark Level */
-		sdmac->watermark_level |= sdmac->watermark_level;
 		/* Address */
 		sdmac->shp_addr = sdmac->per_address;
 		sdmac->per_addr = sdmac->per_address2;