FS#10048 : enable MMU and data cache on Sansa AMS to give a major speed up

- cache IRAM and DRAM
- map IRAM just next to DRAM to remove the need for -mlong-calls and reduce binsize
- tweak delays in Fuze button code
- tweak delays in Clip button code (down button sometimes doesn't respond anyway : an alternate driver is being worked on)

Before reporting any problem, please check your filesystem or format your player from the OF

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21228 a1c6a512-1295-4272-9138-f99709370657

firmware/target/arm/as3525/sansa-fuze/button-fuze.c

@@ -150,7 +150,7 @@ bool button_hold(void)
 
 static void button_delay(void)
 {
-    int i = 24;
+    int i = 50;
     while(i--) asm volatile ("nop\n");
 }