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/thuban_defconfig b/configs/thuban_defconfig
index 70420f0..5872019 100644
--- a/configs/thuban_defconfig
+++ b/configs/thuban_defconfig
@@ -10,3 +10,4 @@
 CONFIG_CMD_GPIO=y
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_SPI_FLASH=y
+CONFIG_SYS_NS16550=y