mfd: altera-sysmgr: Use resource_size function on resource object

drivers/mfd/altera-sysmgr.c:155:36-39: WARNING: Suspicious code. resource_size is maybe missing with res

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

Signed-off-by: Zou Wei <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/altera-sysmgr.c

···
 		if (!base)
 			return -ENOMEM;
 
-		sysmgr_config.max_register = res->end - res->start - 3;
+		sysmgr_config.max_register = resource_size(res) - 3;
 		regmap = devm_regmap_init_mmio(dev, base, &sysmgr_config);
 	}