dmaengine: acpi: Drop double check for ACPI companion device

acpi_dev_get_resources() does perform the NULL pointer check against
ACPI companion device which is given as function parameter. Thus,
there is no need to duplicate this check in the caller.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200622181311.67649-1-andriy.shevchenko@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/acpi-dma.c

@@ -358,19 +358,12 @@ struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,
 {
 	struct acpi_dma_parser_data pdata;
 	struct acpi_dma_spec *dma_spec = &pdata.dma_spec;
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 	struct list_head resource_list;
-	struct acpi_device *adev;
 	struct acpi_dma *adma;
 	struct dma_chan *chan = NULL;
 	int found;
-
-	/* Check if the device was enumerated by ACPI */
-	if (!dev)
-		return ERR_PTR(-ENODEV);
-
-	adev = ACPI_COMPANION(dev);
-	if (!adev)
-		return ERR_PTR(-ENODEV);
+	int ret;
 
 	memset(&pdata, 0, sizeof(pdata));
 	pdata.index = index;
@@ -380,9 +373,11 @@ struct dma_chan *acpi_dma_request_slave_chan_by_index(struct device *dev,
 	dma_spec->slave_id = -1;
 
 	INIT_LIST_HEAD(&resource_list);
-	acpi_dev_get_resources(adev, &resource_list,
+	ret = acpi_dev_get_resources(adev, &resource_list,
 				     acpi_dma_parse_fixed_dma, &pdata);
 	acpi_dev_free_resource_list(&resource_list);
+	if (ret < 0)
+		return ERR_PTR(ret);
 
 	if (dma_spec->slave_id < 0 || dma_spec->chan_id < 0)
 		return ERR_PTR(-ENODEV);