Add support for Cheshire (CVA6), refactor Ariane

Added support for Cheshire (CVA6). Refactored Ariane and Cheshire to use
a shared mach definition since they both implement the CVA6 core and have
common code.

Signed-off-by: Matt Rossouw <matthew.rossouw@unsw.edu.au>

libplatsupport/CMakeLists.txt

@@ -38,6 +38,8 @@ config_choice(
 set(LibPlatSupportMach "")
 if(KernelPlatformRpi3 OR KernelPlatformRpi4)
     set(LibPlatSupportMach "bcm")
+elseif(KernelPlatformCheshire OR KernelPlatformAriane)
+    set(LibPlatSupportMach "cva6")
 elseif(NOT ${KernelArmMach} STREQUAL "")
     # falling back to kernel settings is done to keep legacy compatibility
     set(LibPlatSupportMach "${KernelArmMach}")

libplatsupport/plat_include/cheshire/platsupport/plat/serial.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2019, Data61, CSIRO (ABN 41 687 119 230)
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+#include <autoconf.h>
+
+enum chardev_id {
+    PS_SERIAL0,
+    /* defaults */
+    PS_SERIAL_DEFAULT = PS_SERIAL0
+};
+
+#define PS_SERIAL_DEFAULT 0
+
+#define DEFAULT_SERIAL_PADDR NULL
+#define DEFAULT_SERIAL_INTERRUPT 0