AP_HAL: use ARRAY_SIZE macro

libraries/AP_HAL/examples/Printf/Printf.cpp

@@ -80,7 +80,7 @@ static void test_printf(void)
     char buf[30];
     uint8_t failures = 0;
     hal.console->printf("Running printf tests\n");
-    for (i=0; i<sizeof(float_tests)/sizeof(float_tests[0]); i++) {
+    for (i=0; i < ARRAY_SIZE(float_tests); i++) {
         int ret = hal.util->snprintf(buf, sizeof(buf), float_tests[i].fmt, float_tests[i].v);
         if (strcmp(buf, float_tests[i].result) != 0) {
             hal.console->printf("Failed float_tests[%u] '%s' -> '%s' should be '%s'\n",