dmaengine: fsl-edma: fix miss mutex unlock at an error return path

Use cleanup to manage mutex. Let compiler to do scope guard automatically.

Fixes: 6aa60f79 ("dmaengine: fsl-edma: add safety check for 'srcid'")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/r/202404110915.riwV3ZAC-lkp@intel.com/Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20240411203935.3137158-1-Frank.Li@nxp.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/fsl-edma-common.c

@@ -3,6 +3,7 @@
 // Copyright (c) 2013-2014 Freescale Semiconductor, Inc
 // Copyright (c) 2017 Sysam, Angelo Dureghello  <angelo@sysam.it>
 
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/dmapool.h>
 #include <linux/module.h>

drivers/dma/fsl-edma-main.c

@@ -105,7 +105,8 @@ static struct dma_chan *fsl_edma_xlate(struct of_phandle_args *dma_spec,
 	if (dma_spec->args_count != 2)
 		return NULL;
 
-	mutex_lock(&fsl_edma->fsl_edma_mutex);
+	guard(mutex)(&fsl_edma->fsl_edma_mutex);
+
 	list_for_each_entry_safe(chan, _chan, &fsl_edma->dma_dev.channels, device_node) {
 		if (chan->client_count)
 			continue;
@@ -124,12 +125,10 @@ static struct dma_chan *fsl_edma_xlate(struct of_phandle_args *dma_spec,
 
 				fsl_edma_chan_mux(fsl_chan, fsl_chan->srcid,
 						true);
-				mutex_unlock(&fsl_edma->fsl_edma_mutex);
 				return chan;
 			}
 		}
 	}
-	mutex_unlock(&fsl_edma->fsl_edma_mutex);
 	return NULL;
 }