Update board.h

Use *.icf ram symbal, to avoid hardcode.

bsp/stm32f40x/drivers/board.h

@@ -37,8 +37,14 @@
 
 // <o> Internal SRAM memory size[Kbytes] <8-64>
 //	<i>Default: 64
+#ifdef __ICCARM__
+// Use *.icf ram symbal, to avoid hardcode.
+extern char __ICFEDIT_region_RAM_end__;
+#define STM32_SRAM_END          &__ICFEDIT_region_RAM_end__
+#else
 #define STM32_SRAM_SIZE         128
 #define STM32_SRAM_END          (0x20000000 + STM32_SRAM_SIZE * 1024)
+#endif
 
 // <o> Console on USART: <0=> no console <1=>USART 1 <2=>USART 2 <3=> USART 3
 // 	<i>Default: 1