dmaengine: stm32-dma: fix up error dev_err message

Trivial fix to spelling mistake and make channel plural.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/stm32-dma.c

@@ -1008,7 +1008,7 @@ static struct dma_chan *stm32_dma_of_xlate(struct of_phandle_args *dma_spec,
 
 	c = dma_get_slave_channel(&chan->vchan.chan);
 	if (!c) {
-		dev_err(dev, "No more channel avalaible\n");
+		dev_err(dev, "No more channels available\n");
 		return NULL;
 	}