Fix heap size for NUCLEO_F746ZG on IAR

Author: Mohammad Azim Khan

targets/TARGET_STM/TARGET_STM32F7/TARGET_STM32F746xG/device/TOOLCHAIN_IAR/stm32f746xg.icf

@@ -19,9 +19,9 @@ define region RAM_region = mem:[from __region_RAM_start__ to __region_RAM_end__]
 define region ITCMRAM_region = mem:[from __region_ITCMRAM_start__ to __region_ITCMRAM_end__];
 
 /* Stack and Heap */
-/*Heap 1/4 of ram and stack 1/8*/
+/*Heap 1/4 of ram and stack 1/12 */
 define symbol __size_cstack__ = 0x4000;
-define symbol __size_heap__   = 0x8000;
+define symbol __size_heap__   = 0x13000;
 define block CSTACK    with alignment = 8, size = __size_cstack__   { };
 define block HEAP      with alignment = 8, size = __size_heap__     { };
 define block STACKHEAP with fixed order { block HEAP, block CSTACK };