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

bootloader/sansa_as3525.c

@@ -36,6 +36,8 @@
 #include "power.h"
 
 int show_logo(void);
+
+void main(void) __attribute__((naked, noreturn));
 void main(void)
 {
     unsigned char* loadbuffer;