Sansa Connect: Initial libertas WiFi driver port

Import non-free firmware image from linux-firmware package.

Firmware loading works but is disabled at compile time because just
loading firmware without configuring device results in higher power
consumption without any benefit to end user.

Change-Id: I8fd252c49385ede1ea4e0f9b1e29adeb331ab8ae

apps/main.c

@@ -36,6 +36,7 @@
 #include "panic.h"
 #include "menu.h"
 #include "usb.h"
+#include "wifi.h"
 #include "powermgmt.h"
 #if !defined(DX50) && !defined(DX90)
 #include "adc.h"
@@ -636,6 +637,10 @@ static void init(void)
     CHART("<audio_init");
     talk_announce_voice_invalid(); /* notify user w/ voice prompt if voice file invalid */
 
+#ifdef HAVE_WIFI
+    wifi_init();
+#endif
+
     /* runtime database has to be initialized after audio_init() */
     cpu_boost(false);