test_firmware: fix error return getting clobbered

In the case where eq->fw->size > PAGE_SIZE the error return rc
is being set to EINVAL however this is being overwritten to
rc = req->fw->size because the error exit path via label 'out' is
not being taken.  Fix this by adding the jump to the error exit
path 'out'.

Detected by CoverityScan, CID#1453465 ("Unused value")

Fixes: c92316bf8e94 ("test_firmware: add batched firmware tests")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

lib/test_firmware.c

@@ -837,6 +837,7 @@ static ssize_t read_firmware_show(struct device *dev,
 	if (req->fw->size > PAGE_SIZE) {
 		pr_err("Testing interface must use PAGE_SIZE firmware for now\n");
 		rc = -EINVAL;
+		goto out;
 	}
 	memcpy(buf, req->fw->data, req->fw->size);