Nuke maemo (nokian800/nokian900) and [open]pandora targets

They haven't seen any work since 2013, and likely hasn't compiled in at
least a couple of releases -- not that we ever "released" anything for
these targets.

Futhermore, upstream for both has been effectively dead for about as
long, and there's been no user reports of these being used since 2017
(and even then only in passing).

It isn't worth the effort to triage their current state, much less
uplift into something supportable, while the maintenance burden of
keeping these things in-tree can be demonstrated by the diffstat.

Change-Id: Id93bd450679d1b75e2c74295b3ae1548cd241b24

firmware/export/config.h

@@ -95,11 +95,7 @@
 #define PLATFORM_HOSTED  (1<<1)
 #define PLATFORM_ANDROID (1<<2)
 #define PLATFORM_SDL     (1<<3)
-#define PLATFORM_MAEMO4  (1<<4)
-#define PLATFORM_MAEMO5  (1<<5)
-#define PLATFORM_MAEMO   (PLATFORM_MAEMO4|PLATFORM_MAEMO5)
-#define PLATFORM_PANDORA (1<<6)
-#define PLATFORM_CTRU    (1<<7)
+#define PLATFORM_CTRU    (1<<4)
 
 /* CONFIG_KEYPAD */
 #define IRIVER_H100_PAD     4
@@ -538,12 +534,6 @@ Lyre prototype 1 */
 #include "config/sdlapp.h"
 #elif defined(ANDROID)
 #include "config/android.h"
-#elif defined(NOKIAN8XX)
-#include "config/nokian8xx.h"
-#elif defined(NOKIAN900)
-#include "config/nokian900.h"
-#elif defined(PANDORA)
-#include "config/pandora.h"
 #elif defined(SAMSUNG_YPR0)
 #include "config/samsungypr0.h"
 #elif defined(CREATIVE_ZENXFI)
@@ -1427,7 +1417,6 @@ Lyre prototype 1 */
 #endif
 
 #if defined(HAVE_SDL_AUDIO) \
-    && !(CONFIG_PLATFORM & PLATFORM_MAEMO5) \
     && !defined(HAVE_SW_VOLUME_CONTROL)
 /* SW volume is needed for accurate control and no double buffering should be
  * required. If target uses SW volume, then its definitions are used instead