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/qemu_mipsel_defconfig b/configs/qemu_mipsel_defconfig
index bfb3bcc..d851075 100644
--- a/configs/qemu_mipsel_defconfig
+++ b/configs/qemu_mipsel_defconfig
@@ -4,4 +4,5 @@
 # CONFIG_CMD_LOADB is not set
 # CONFIG_CMD_LOADS is not set
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_SYS_NS16550=y
 CONFIG_USE_PRIVATE_LIBGCC=y