Fix PRINTF_ARGS Coverity issue

Fixes:

test/acl_context_test.cpp:769:3:
  Type: Invalid type in argument to printf format specifier (PRINTF_ARGS)

test/acl_context_test.cpp:769:3:
  invalid_type: Argument "acl_ref_count(context0)" to format specifier "%lu" was expected to have type "unsigned long" but has type "unsigned int".
src/acl_hal.cpp:123:3:
  path: Condition "debug_mode > 0", taking true branch.
src/acl_hal.cpp:126:5:
  printf_function: Calling "vprintf" which uses a "printf"-style format string. [Note: The source code implementation of the function has been overridden by a builtin model.]

Author: IlanTruanovsky

test/acl_context_test.cpp

@@ -766,7 +766,7 @@ MT_TEST(Context, create_context_multi) {
   ACL_LOCKED(CHECK(acl_context_is_valid(context0)));
   ACL_LOCKED(CHECK(acl_is_valid_ptr(context0)));
 
-  ACL_LOCKED(acl_print_debug_msg(" newly created context0 <%lu>\n",
+  ACL_LOCKED(acl_print_debug_msg(" newly created context0 <%u>\n",
                                  acl_ref_count(context0)));
 
   status = CL_INVALID_DEVICE;