refactor(ast2700): adopt RESET_TO_BL31 boot flow

Revise the AST2700 boot flow to the RESET_TO_BL31 scheme.
The execution of BL1/2 can be saved from ARM CA35 while most
low level platform initialization are moved to a preceding MCU.

This patch updates the build configuration and also adds
the SMP mailbox setup code to hold secondary cores until
they are being waken up.

Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
Change-Id: I7e0aa6416b92b97036153db1d9a26baaa41b7b18
diff --git a/plat/aspeed/ast2700/include/platform_reg.h b/plat/aspeed/ast2700/include/platform_reg.h
index 20ae32a..7f26865 100644
--- a/plat/aspeed/ast2700/include/platform_reg.h
+++ b/plat/aspeed/ast2700/include/platform_reg.h
@@ -18,11 +18,10 @@
 #define UART12_BASE	(UART_BASE + 0xb00)
 
 /* CPU-die SCU */
-#define SCU_CPU_BASE		U(0x12c02000)
-#define SCU_CPU_SMP_READY	(SCU_CPU_BASE + 0x780)
-#define SCU_CPU_SMP_EP1		(SCU_CPU_BASE + 0x788)
-#define SCU_CPU_SMP_EP2		(SCU_CPU_BASE + 0x790)
-#define SCU_CPU_SMP_EP3		(SCU_CPU_BASE + 0x798)
-#define SCU_CPU_SMP_POLLINSN	(SCU_CPU_BASE + 0x7a0)
+#define SCU_CPU_BASE	U(0x12c02000)
+#define SCU_CPU_SMP_EP0	(SCU_CPU_BASE + 0x780)
+#define SCU_CPU_SMP_EP1	(SCU_CPU_BASE + 0x788)
+#define SCU_CPU_SMP_EP2	(SCU_CPU_BASE + 0x790)
+#define SCU_CPU_SMP_EP3	(SCU_CPU_BASE + 0x798)
 
 #endif /* PLATFORM_REG_H */