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/PLU405_defconfig b/configs/PLU405_defconfig
index a691e24..546376f 100644
--- a/configs/PLU405_defconfig
+++ b/configs/PLU405_defconfig
@@ -5,3 +5,4 @@
 CONFIG_AUTOBOOT_PROMPT="Press SPACE to abort autoboot in %d seconds\n"
 CONFIG_AUTOBOOT_STOP_STR=" "
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_SYS_NS16550=y