Greentea: Fix flash overflown issue in callback_big test

- The "Callback_big" greentea test has six test cases that require a
minimum above 36kb ROM to build all test cases. LPC1114 target has only
32KB ROM memory, so the limit number of test cases to build with ROM
size minimum check to include 6th test case.

Note:
In LPC1114 target, callback_big test has ROM overflow build issue
for both Mbed CLI1 and CLI2.

Author: rajkan01

platform/tests/TESTS/mbed_functional/callback/main.cpp

@@ -20,6 +20,8 @@
 #include "utest.h"
 #include <mstd_functional>
 
+#define TEST_MIN_REQ_ROM_SIZE (36 * 1024)
+
 using namespace utest::v1;
 
 template <typename T>
@@ -884,10 +886,10 @@ Case cases[] = {
     Case("Testing callbacks with 2 uint64s", test_dispatch2<uint64_t>),
     Case("Testing callbacks with 3 uint64s", test_dispatch3<uint64_t>),
     Case("Testing callbacks with 4 uint64s", test_dispatch4<uint64_t>),
-// IAR currently crashes at link time with this test - skip it as it's well beyond anything needed by real code
-#ifndef __ICCARM__
+#if !defined(__ICCARM__) && defined(MBED_ROM_SIZE) && (MBED_ROM_SIZE >= TEST_MIN_REQ_ROM_SIZE)
     Case("Testing callbacks with 5 uint64s", test_dispatch5<uint64_t>),
 #endif
+//#endif
 #elif DO_SMALL_TEST
     Case("Testing callbacks with 0 uchars", test_dispatch0<unsigned char>),
     Case("Testing callbacks with 1 uchars", test_dispatch1<unsigned char>),