staging: rtl8192u: check dev_alloc_skb() return value in fw_download_code()

This patch adds a check whether skb allocation, in fw_download_code(), was
successful.
Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8192u/r819xU_firmware.c

@@ -62,6 +62,8 @@ bool fw_download_code(struct net_device *dev, u8 *code_virtual_address, u32 buff
 		 * add 4 to avoid packet appending overflow.
 		 * */
 		skb  = dev_alloc_skb(USB_HWDESC_HEADER_LEN + frag_length + 4);
+		if (!skb)
+			return false;
 		memcpy((unsigned char *)(skb->cb),&dev,sizeof(dev));
 		tcb_desc = (cb_desc *)(skb->cb + MAX_DEV_ADDR_SIZE);
 		tcb_desc->queue_index = TXCMD_QUEUE;