include: move MHZ_TICKS_PER_SEC to utils_def.h

This patch moves the MHZ_TICKS_PER_SEC macro to utils_def.h
for other platforms to use.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Change-Id: I6c4dc733f548d73cfdb3515ec9ad89a9efaf4407
diff --git a/drivers/delay_timer/generic_delay_timer.c b/drivers/delay_timer/generic_delay_timer.c
index 3d0a11f..ca522e0 100644
--- a/drivers/delay_timer/generic_delay_timer.c
+++ b/drivers/delay_timer/generic_delay_timer.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2020, NVIDIA Corporation. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -12,11 +13,9 @@
 #include <common/debug.h>
 #include <drivers/delay_timer.h>
 #include <drivers/generic_delay_timer.h>
+#include <lib/utils_def.h>
 #include <plat/common/platform.h>
 
-/* Ticks elapsed in one second by a signal of 1 MHz */
-#define MHZ_TICKS_PER_SEC 1000000
-
 static timer_ops_t ops;
 
 static uint32_t get_timer_value(void)