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/MIP405T_defconfig b/configs/MIP405T_defconfig
index 22b82b1..799a1b6 100644
--- a/configs/MIP405T_defconfig
+++ b/configs/MIP405T_defconfig
@@ -3,3 +3,4 @@
 CONFIG_TARGET_MIP405=y
 CONFIG_SYS_EXTRA_OPTIONS="MIP405T"
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_SYS_NS16550=y