Replace hard coded heap size value with calculation

Author: harrisonmutai-arm

targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC54114/device/TARGET_LPC54114_M4/TOOLCHAIN_ARM_STD/LPC54114J256_cm4.sct

@@ -93,7 +93,7 @@
 #if (defined(__heap_size__))
   #define Heap_Size                    __heap_size__
 #else
-  #define Heap_Size                    0x0400
+  #define Heap_Size                    (m_data_size - Stack_Size - (AlignExpr(ImageLimit(RW_IRAM1), 16) - m_data_start))
 #endif
 
 LR_IROM1 m_interrupts_start m_text_start+m_text_size-m_interrupts_start { ; load region size_region

targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_MCU_LPC546XX/device/TOOLCHAIN_ARM_STD/LPC54628J512.sct

@@ -85,7 +85,7 @@
 #if (defined(__heap_size__))
   #define Heap_Size                    __heap_size__
 #else
-  #define Heap_Size                    0x0400
+  #define Heap_Size                    (m_data_size - Stack_Size - (AlignExpr(ImageLimit(RW_IRAM1), 16) - m_data_start))
 #endif
 
 LR_IROM1 m_interrupts_start m_text_start+m_text_size-m_interrupts_start { ; load region size_region