mwiflex: avoid possible null pointer dereference

Do not dereference card before checking against NULL value.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

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

@@ -2901,10 +2901,11 @@ static void mwifiex_unregister_dev(struct mwifiex_adapter *adapter)
 {
 	struct pcie_service_card *card = adapter->card;
 	const struct mwifiex_pcie_card_reg *reg;
-	struct pci_dev *pdev = card->dev;
+	struct pci_dev *pdev;
 	int i;
 
 	if (card) {
+		pdev = card->dev;
 		if (card->msix_enable) {
 			for (i = 0; i < MWIFIEX_NUM_MSIX_VECTORS; i++)
 				synchronize_irq(card->msix_entries[i].vector);