x1000: use core_alloc in bootloader for loading rockbox

Using the audio buffer directly is a bad idea because this will
render core_alloc non-functional if load_firmware() writes into
the buffer but then fails, for example on a checksum mismatch.

Change-Id: Ib2d17bcea53bdea1c4c5496cec0c4eee5dd66069

firmware/target/mips/ingenic_x1000/app.lds

@@ -88,10 +88,8 @@ SECTIONS
     {
         . = ALIGN(4);
         audiobuffer = .;
-        loadbuffer = .;
     } > DRAM
 
-    loadbufferend = ENDAUDIOADDR;
     audiobufend = ENDAUDIOADDR;
     codecbuf = ENDAUDIOADDR;
     pluginbuf = ENDCODECADDR;