cw1200: Delete an unnecessary check before the function call "release_firmware"

The release_firmware() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/cw1200/fwio.c

@@ -246,8 +246,7 @@ static int cw1200_load_firmware_cw1200(struct cw1200_common *priv)
 
 error:
 	kfree(buf);
-	if (firmware)
-		release_firmware(firmware);
+	release_firmware(firmware);
 	return ret;
 
 #undef APB_WRITE