mwifiex: remove function pointer check

clang static analyzer reports this problem

init.c:739:8: warning: Called function pointer
  is null (null dereference)
        ret = adapter->if_ops.check_fw_status( ...
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In mwifiex_dnld_fw, there is an earlier check for check_fw_status(),
The check was introduced for usb support at the same time this
check in _mwifiex_fw_dpc() was made

	if (adapter->if_ops.dnld_fw) {
		ret = adapter->if_ops.dnld_fw(adapter, &fw);
	} else {
		ret = mwifiex_dnld_fw(adapter, &fw);
	}

And a dnld_fw function initialized as part the usb's
mwifiex_if_ops.

The other instances of mwifiex_if_ops for pci and sdio
both set check_fw_status.

So the first check is not needed and can be removed.

Fixes: 4daffe35 ("mwifiex: add support for Marvell USB8797 chipset")
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200906200548.18053-1-trix@redhat.com

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

@@ -695,14 +695,12 @@ int mwifiex_dnld_fw(struct mwifiex_adapter *adapter,
 	int ret;
 	u32 poll_num = 1;
 
-	if (adapter->if_ops.check_fw_status) {
-		/* check if firmware is already running */
-		ret = adapter->if_ops.check_fw_status(adapter, poll_num);
-		if (!ret) {
-			mwifiex_dbg(adapter, MSG,
-				    "WLAN FW already running! Skip FW dnld\n");
-			return 0;
-		}
+	/* check if firmware is already running */
+	ret = adapter->if_ops.check_fw_status(adapter, poll_num);
+	if (!ret) {
+		mwifiex_dbg(adapter, MSG,
+			    "WLAN FW already running! Skip FW dnld\n");
+		return 0;
 	}
 
 	/* check if we are the winner for downloading FW */