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/nokia_rx51_defconfig b/configs/nokia_rx51_defconfig
index 21959a6..d7eb39a 100644
--- a/configs/nokia_rx51_defconfig
+++ b/configs/nokia_rx51_defconfig
@@ -12,3 +12,4 @@
 # CONFIG_CMD_SETEXPR is not set
 # CONFIG_CMD_NET is not set
 # CONFIG_CMD_NFS is not set
+CONFIG_SYS_NS16550=y