mwifiex: avoid [-Wmaybe-uninitialized] warnings in pcie.c

drivers/net/wireless/mwifiex/pcie.c:1157:9: warning:
  'desc2' may be used uninitialized in this function
  [-Wmaybe-uninitialized]
drivers/net/wireless/mwifiex/pcie.c:1048:31: note:
  'desc2' was declared here

drivers/net/wireless/mwifiex/pcie.c:1159:9: warning:
  'desc' may be used uninitialized in this function
  [-Wmaybe-uninitialized]
drivers/net/wireless/mwifiex/pcie.c:1047:32: note:
  'desc' was declared here

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/pcie.c

@@ -1030,8 +1030,8 @@ mwifiex_pcie_send_data(struct mwifiex_adapter *adapter, struct sk_buff *skb,
 	u32 wrindx, num_tx_buffs, rx_val;
 	int ret;
 	dma_addr_t buf_pa;
-	struct mwifiex_pcie_buf_desc *desc;
-	struct mwifiex_pfu_buf_desc *desc2;
+	struct mwifiex_pcie_buf_desc *desc = NULL;
+	struct mwifiex_pfu_buf_desc *desc2 = NULL;
 	__le16 *tmp;
 
 	if (!(skb->data && skb->len)) {