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/vct_premium_defconfig b/configs/vct_premium_defconfig
index 2ae4975..7ca6e34 100644
--- a/configs/vct_premium_defconfig
+++ b/configs/vct_premium_defconfig
@@ -3,4 +3,5 @@
 CONFIG_VCT_PREMIUM=y
 CONFIG_SYS_PROMPT="$ "
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_SYS_NS16550=y
 CONFIG_USE_PRIVATE_LIBGCC=y