phy: fix resource_size.cocci warnings

drivers/phy/microchip/sparx5_serdes.c:2440:54-57: ERROR: Missing resource_size with iores

 Use resource_size function on resource object
 instead of explicit computation.

Generated by: scripts/coccinelle/api/resource_size.cocci

Fixes: 2ff8a1ee ("phy: Add Sparx5 ethernet serdes PHY driver")
CC: Steen Hegelund <steen.hegelund@microchip.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20210318232844.GA65886@63b0c5462fdaSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/microchip/sparx5_serdes.c

@@ -2470,7 +2470,7 @@ static int sparx5_serdes_probe(struct platform_device *pdev)
 	priv->coreclock = clock;
 
 	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	iomem = devm_ioremap(priv->dev, iores->start, iores->end - iores->start + 1);
+	iomem = devm_ioremap(priv->dev, iores->start, resource_size(iores));
 	if (IS_ERR(iomem)) {
 		dev_err(priv->dev, "Unable to get serdes registers: %s\n",
 			iores->name);