include/configs: aspeed: Remove hardcoded variables

The hardcoded platform variables such as DRAM base address are not
common to Aspeed SoCs AST24xx/AST25xx/AST26xx. This patch replaces
those hardcoded with macros defined in a newly added header, where
the basic SoC HW information are assigned accordingly.

Signed-off-by: Chia-Wei, Wang <chiawei_wang@aspeedtech.com>

arch/arm/include/asm/arch-aspeed/platform.h

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) ASPEED Technology Inc.
+ * Ryan Chen <ryan_chen@aspeedtech.com>
+ *
+ */
+
+#ifndef _ASM_ARCH_PLATFORM_H
+#define _ASM_ARCH_PLATFORM_H
+
+#if defined(CONFIG_ASPEED_AST2500)
+#define ASPEED_MAC_COUNT	2
+#define ASPEED_DRAM_BASE	0x80000000
+#define ASPEED_SRAM_BASE	0x1e720000
+#define ASPEED_SRAM_SIZE	0x9000
+#else
+#err "Unrecognized Aspeed platform."
+#endif
+
+#endif