Merge pull request #2900 from c1728p9/ncs_heap

NCS36510 - decrease reserved heap space

Author: sg-

targets/cmsis/TARGET_ONSEMI/TARGET_NCS36510/TOOLCHAIN_GCC_ARM/NCS36510.ld

@@ -205,7 +205,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*);
-        . += 0x4000;
+        . += 0x800;
         __HeapLimit = .;
     } > RAM
     PROVIDE(__heap_size = SIZEOF(.heap));