mwifiex: process pcie io memory read failure case

It is observed that ioread32 may fail to read pcie register
in certain scenarios, this patch handles these cases.

Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/pcie.c

@@ -323,6 +323,8 @@ static int mwifiex_read_reg(struct mwifiex_adapter *adapter, int reg, u32 *data)
 	struct pcie_service_card *card = adapter->card;
 
 	*data = ioread32(card->pci_mmap1 + reg);
+	if (*data == 0xffffffff)
+		return 0xffffffff;
 
 	return 0;
 }