ns16550: move CONFIG_SYS_NS16550 to Kconfig

Move CONFIG_SYS_NS16550 to Kconfig, and run moveconfig.py.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
diff --git a/configs/axs101_defconfig b/configs/axs101_defconfig
index 8e5d2e5..52d5e2f 100644
--- a/configs/axs101_defconfig
+++ b/configs/axs101_defconfig
@@ -18,4 +18,5 @@
 CONFIG_CLK=y
 CONFIG_DM_ETH=y
 CONFIG_ETH_DESIGNWARE=y
+CONFIG_SYS_NS16550=y
 CONFIG_USE_PRIVATE_LIBGCC=y