intel_adsp: ace: Fix heap in the linker

The end of the heap should be the same as _heap_sentry. The current end
marker just covers the range of memory that is explicitly put in
.heap_memand not account until the end of L2_SRAM_BASE +
L2_SRAM_SIZE memory.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>

soc/xtensa/intel_adsp/ace/ace-link.ld

@@ -395,7 +395,6 @@ SECTIONS {
   {
     _heap_start = .;
     *(.heap_mem)
-    _heap_end = .;
   } >ucram
 
   .unused_ram_start_marker SEGSTART_CACHED (NOLOAD) :
@@ -408,6 +407,7 @@ SECTIONS {
 
   . = L2_SRAM_BASE + L2_SRAM_SIZE;
   . = SEGSTART_UNCACHED;
+  _heap_end = .;
   _heap_sentry = .;
 
   /* dma buffers */