[media] as102: fix potential double free in as102_fw_upload()

In case the request to locate the firmware file part 2 fails, the error
path releases the already freed firmware memory location again. Thus
reset the firmware pointer to NULL after releasing firmware file part 1.
Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/as102/as102_fw.c

@@ -198,6 +198,7 @@ int as102_fw_upload(struct as10x_bus_adapter_t *bus_adap)
 	pr_info("%s: firmware: %s loaded with success\n",
 		DRIVER_NAME, fw1);
 	release_firmware(firmware);
+	firmware = NULL;
 
 	/* wait for boot to complete */
 	mdelay(100);