Remove unused heap_size define

Author: deepikabhavnani

targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_K66F/device/TOOLCHAIN_GCC_ARM/MK66FN2M0xxx18.ld

@@ -57,8 +57,6 @@ __ram_vector_table__ = 1;
  * the stack where main runs is determined via the RTOS. */
 __stack_size__ = MBED_BOOT_STACK_SIZE;
 
-__heap_size__ = 0x6000;
-
 #if !defined(MBED_APP_START)
   #define MBED_APP_START 0
 #endif

targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_KL43Z/device/TOOLCHAIN_GCC_ARM/MKL43Z256xxx4.ld

@@ -58,9 +58,6 @@ __ram_vector_table__ = 1;
  * the stack where main runs is determined via the RTOS. */
 __stack_size__ = MBED_BOOT_STACK_SIZE;
 
-__heap_size__ = 0x2800;
-
-HEAP_SIZE  = DEFINED(__heap_size__)  ? __heap_size__  : 0x0400;
 STACK_SIZE = DEFINED(__stack_size__) ? __stack_size__ : 0x0400;
 M_VECTOR_RAM_SIZE = DEFINED(__ram_vector_table__) ? 0x0200 : 0x0;
 

targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_KL82Z/device/TOOLCHAIN_GCC_ARM/MKL82Z128xxx7.ld

@@ -61,9 +61,6 @@ __ram_vector_table__ = 1;
  * the stack where main runs is determined via the RTOS. */
 __stack_size__ = MBED_BOOT_STACK_SIZE;
 
-__heap_size__ = 0x6000;
-
-HEAP_SIZE  = DEFINED(__heap_size__)  ? __heap_size__  : 0x0400;
 STACK_SIZE = DEFINED(__stack_size__) ? __stack_size__ : 0x0400;
 M_VECTOR_RAM_SIZE = DEFINED(__ram_vector_table__) ? 0x0140 : 0x0;