plat/arm: mhu: Move to drivers/ folder

Change-Id: I656753a1825ea7340a3708b950fa6b57455e9056
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/plat/arm/board/juno/juno_topology.c b/plat/arm/board/juno/juno_topology.c
index d83bd9a..ca5c344 100644
--- a/plat/arm/board/juno/juno_topology.c
+++ b/plat/arm/board/juno/juno_topology.c
@@ -4,14 +4,13 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <drivers/arm/css/css_mhu_doorbell.h>
 #include <drivers/arm/css/scmi.h>
 #include <plat/arm/common/plat_arm.h>
 #include <plat/arm/css/common/css_pm.h>
 #include <plat/common/platform.h>
 #include <platform_def.h>
 
-#include "../../css/drivers/mhu/css_mhu_doorbell.h"
-
 #if CSS_USE_SCMI_SDS_DRIVER
 static scmi_channel_plat_info_t juno_scmi_plat_info = {
 		.scmi_mbx_mem = CSS_SCMI_PAYLOAD_BASE,