dmaengine: sa11x0: Mark PM functions as __maybe_unused

Without CONFIG_PM_SLEEP, the runtime suspend/resume functions
are unused, producing a warning:

../drivers/dma/sa11x0-dma.c:1042:12: error: 'sa11x0_dma_resume' defined but not used
../drivers/dma/sa11x0-dma.c:1004:12: error: 'sa11x0_dma_suspend' defined but not used
Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Link: https://lore.kernel.org/r/20211026020508.550-1-caihuoqing@baidu.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/sa11x0-dma.c

@@ -1001,7 +1001,7 @@ static int sa11x0_dma_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static int sa11x0_dma_suspend(struct device *dev)
+static __maybe_unused int sa11x0_dma_suspend(struct device *dev)
 {
 	struct sa11x0_dma_dev *d = dev_get_drvdata(dev);
 	unsigned pch;
@@ -1039,7 +1039,7 @@ static int sa11x0_dma_suspend(struct device *dev)
 	return 0;
 }
 
-static int sa11x0_dma_resume(struct device *dev)
+static __maybe_unused int sa11x0_dma_resume(struct device *dev)
 {
 	struct sa11x0_dma_dev *d = dev_get_drvdata(dev);
 	unsigned pch;