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/fx12mm_flash_defconfig b/configs/fx12mm_flash_defconfig
index 60eee67..ac38412 100644
--- a/configs/fx12mm_flash_defconfig
+++ b/configs/fx12mm_flash_defconfig
@@ -6,3 +6,4 @@
 # CONFIG_CMD_SETEXPR is not set
 # CONFIG_CMD_NET is not set
 # CONFIG_CMD_NFS is not set
+CONFIG_SYS_NS16550=y