soc/riscv: Instead of use Kconfig items to compiler flags. [1/1]

PD#SWPL-68240

Problem:
Refactor for all.

Solution:
Instead of use Kconfig items to compiler flags.

Verify:
N/A

Change-Id: If43d62932f542ee9d0466047cc79198b2f693fa4
Signed-off-by: Xiaohu.Huang <xiaohu.huang@amlogic.com>
diff --git a/Kconfig b/Kconfig
index fb3cad3..e56548f 100644
--- a/Kconfig
+++ b/Kconfig
@@ -4,3 +4,12 @@
 
 source "soc/riscv/t5d/Kconfig"
 source "soc/riscv/t5w/Kconfig"
+
+choice
+	prompt "Serial"
+	default N200_REVA
+	config N200_REVA
+	bool "N200 REVA"
+	help
+	  Enable N200 REVA serial of RISCV.
+endchoice