tsnep: Fix resource_size cocci warning

The following warning is fixed, by removing the unused resource size:

drivers/net/ethernet/engleder/tsnep_main.c:1155:21-24:
WARNING: Suspicious code. resource_size is maybe missing with io
Reported-by: Nkernel test robot <lkp@intel.com>
Reported-by: NAbaci Robot <abaci@linux.alibaba.com>
Signed-off-by: NGerhard Engleder <gerhard@engleder-embedded.com>
Link: https://lore.kernel.org/r/20211124205225.13985-1-gerhard@engleder-embedded.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/engleder/tsnep.h

@@ -125,7 +125,6 @@ struct tsnep_adapter {
 	struct platform_device *pdev;
 	struct device *dmadev;
 	void __iomem *addr;
-	unsigned long size;
 	int irq;
 
 	bool gate_control;

drivers/net/ethernet/engleder/tsnep_main.c

@@ -1152,7 +1152,6 @@ static int tsnep_probe(struct platform_device *pdev)
 	adapter->addr = devm_ioremap_resource(&pdev->dev, io);
 	if (IS_ERR(adapter->addr))
 		return PTR_ERR(adapter->addr);
-	adapter->size = io->end - io->start + 1;
 	adapter->irq = platform_get_irq(pdev, 0);
 	netdev->mem_start = io->start;
 	netdev->mem_end = io->end;