drivers/mhu: derive doorbell base address

In order to allow the MHUv2 driver to be usable with multiple MHUv2
controllers, use the base address of the controller from the platform
information instead of the MHUV2_BASE_ADDR macro.

Change-Id: I4dbab87b929fb0568935e6c8b339ce67937f8cd1
Signed-off-by: Aditya Angadi <aditya.angadi@arm.com>
diff --git a/plat/socionext/synquacer/include/platform_def.h b/plat/socionext/synquacer/include/platform_def.h
index 7158bfa..b87ac3f 100644
--- a/plat/socionext/synquacer/include/platform_def.h
+++ b/plat/socionext/synquacer/include/platform_def.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -80,7 +80,6 @@
 #define DRAMINFO_BASE			0x2E00FFC0
 
 #define PLAT_SQ_MHU_BASE		0x45000000
-#define PLAT_MHUV2_BASE			0xFFFFFFFF /* MHUV2 is not supported */
 
 #define PLAT_SQ_SCP_COM_SHARED_MEM_BASE		0x45400000
 #define SCPI_CMD_GET_DRAMINFO			0x1