riscv: configs: Support AE350 SMP booting from flash flow

Add two defconfigs to support AE350 SMP booting from flash.

Signed-off-by: Rick Chen <rick@andestech.com>
Cc: Greentime Hu <greentime@andestech.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de>
diff --git a/board/AndesTech/ax25-ae350/MAINTAINERS b/board/AndesTech/ax25-ae350/MAINTAINERS
index b0a99e4..feed5d1 100644
--- a/board/AndesTech/ax25-ae350/MAINTAINERS
+++ b/board/AndesTech/ax25-ae350/MAINTAINERS
@@ -5,3 +5,5 @@
 F:	include/configs/ax25-ae350.h
 F:	configs/ae350_rv32_defconfig
 F:	configs/ae350_rv64_defconfig
+F:	configs/ae350_rv32_xip_defconfig
+F:	configs/ae350_rv64_xip_defconfig