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/app.lds

@@ -55,6 +55,12 @@ SECTIONS
 {
     loadaddress = DRAM_ORIG;
 
+    .vectors :
+    {
+        _vectors_start = .;
+        *(.init.text)
+    } > DRAM
+
     .text :
     {
         _loadaddress = .;
@@ -83,14 +89,6 @@ SECTIONS
         *(.eh_frame)
     }
 
-    .vectors IRAMORIG:
-    {
-        _vectors_start = .;
-        *(.init.text)
-    } > IRAM AT > DRAM
-
-    _vectorscopy = LOADADDR(.vectors);
-
     .iram :
     {
         _iramstart = .;