Target_STM:_sbrk updated to use limits from linker files no need to set defines

_sbrk uses the exports from linker file __end and __HeapLimit to allocate memory
in heap. Linker scripts were updated accordingly to set the limits.

Author: Deepika

targets/TARGET_STM/TARGET_STM32F0/TARGET_DISCO_F051R8/device/TOOLCHAIN_GCC_ARM/STM32F0xx.ld

@@ -138,6 +138,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*)
+        . = ORIGIN(RAM) + LENGTH(RAM) - STACK_SIZE;
         __HeapLimit = .;
     } > RAM
 

targets/TARGET_STM/TARGET_STM32F0/TARGET_NUCLEO_F030R8/device/TOOLCHAIN_GCC_ARM/STM32F030X8.ld

@@ -137,6 +137,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*)
+        . = ORIGIN(RAM) + LENGTH(RAM) - STACK_SIZE;
         __HeapLimit = .;
     } > RAM
 

targets/TARGET_STM/TARGET_STM32F0/TARGET_NUCLEO_F031K6/device/TOOLCHAIN_GCC_ARM/STM32F031X6.ld

@@ -137,6 +137,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*)
+        . = ORIGIN(RAM) + LENGTH(RAM) - STACK_SIZE;
         __HeapLimit = .;
     } > RAM
 

targets/TARGET_STM/TARGET_STM32F0/TARGET_NUCLEO_F042K6/device/TOOLCHAIN_GCC_ARM/STM32F042X6.ld

@@ -137,6 +137,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*)
+        . = ORIGIN(RAM) + LENGTH(RAM) - STACK_SIZE;
         __HeapLimit = .;
     } > RAM
 

targets/TARGET_STM/TARGET_STM32F0/TARGET_NUCLEO_F070RB/device/TOOLCHAIN_GCC_ARM/STM32F0xxx_retarget.c

@@ -137,6 +137,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*)
+        . = ORIGIN(RAM) + LENGTH(RAM) - StackSize;
         __HeapLimit = .;
     } > RAM
 

targets/TARGET_STM/TARGET_STM32F0/TARGET_NUCLEO_F072RB/device/TOOLCHAIN_GCC_ARM/STM32F0xxx_retarget.c

@@ -138,6 +138,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*)
+        . = ORIGIN(RAM) + LENGTH(RAM) - STACK_SIZE;
         __HeapLimit = .;
     } > RAM
 

targets/TARGET_STM/TARGET_STM32F0/TARGET_NUCLEO_F091RC/device/TOOLCHAIN_GCC_ARM/STM32F091XC.ld

@@ -138,6 +138,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*)
+        . = ORIGIN(RAM) + LENGTH(RAM) - STACK_SIZE;
         __HeapLimit = .;
     } > RAM
 

targets/TARGET_STM/TARGET_STM32F1/TARGET_BLUEPILL_F103C8/device/TOOLCHAIN_GCC_ARM/STM32F103XB.ld

@@ -138,6 +138,7 @@ SECTIONS
         __end__ = .;
         end = __end__;
         *(.heap*)
+        . = ORIGIN(RAM) + LENGTH(RAM) - STACK_SIZE;
         __HeapLimit = .;
     } > RAM