[netdrvr] smc91x: fix resource removal (null ptr deref)

Properly handle resource cleanup on unplug/exit.

Spotted by Jonathan Cameron
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/net/smc91x.c

@@ -2255,7 +2255,7 @@ static int smc_drv_remove(struct platform_device *pdev)
 
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "smc91x-regs");
 	if (!res)
-		platform_get_resource(pdev, IORESOURCE_MEM, 0);
+		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	release_mem_region(res->start, SMC_IO_EXTENT);
 
 	free_netdev(ndev);