Plugins: modify IRAM copying code

Move to plugin_crt0.c, plugins don't need PLUGIN_IRAM_* macros anymore
IRAM is no longered zeroed before copying (as it is at the same address
than BSS) -> Fix FS#11581
Use cpucache_invalidate() (and not cpucache_flush), needed for self-modifying code on cached IRAM

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@27948 a1c6a512-1295-4272-9138-f99709370657

apps/plugins/pdbox/pdbox.c

@@ -29,8 +29,6 @@
 
 /* Welcome to the PDBox plugin */
 
-PLUGIN_IRAM_DECLARE
-
 /* Name of the file to open. */
 char* filename;
 
@@ -159,8 +157,6 @@ void core_thread(void)
 /* Plug-in entry point */
 enum plugin_status plugin_start(const void* parameter)
 {
-    PLUGIN_IRAM_INIT(rb)
-
     /* Memory pool variables. */
     size_t mem_size;
     void* mem_pool;