On STM32F439xI IAR linker file decreased stack size and increased heap

Decreased stack size from 24kB to 1kB (stack is used on boot-up/interrupt
handler). Increased heap size from 65kB to 89kB.

Change is related to issue #7137
where UBLOX_EVK_ODIN_W2 runs out of heap on WLAN.

targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F439xI/device/TOOLCHAIN_IAR/stm32f439xx_flash.icf

@@ -15,9 +15,9 @@ define symbol __ICFEDIT_region_RAM_end__      = 0x2002FFFF;
 define symbol __ICFEDIT_region_CCMRAM_start__ = 0x10000000;
 define symbol __ICFEDIT_region_CCMRAM_end__   = 0x1000FFFF;
 /*-Sizes-*/
-/*Heap 64kB and stack 24kB */
-define symbol __ICFEDIT_size_cstack__ = 0x6000;
-define symbol __ICFEDIT_size_heap__   = 0x10000;
+/*Heap 89kB and stack 1kB */
+define symbol __ICFEDIT_size_cstack__ = 0x400;
+define symbol __ICFEDIT_size_heap__   = 0x15C00;
 /**** End of ICF editor section. ###ICF###*/