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/Hummingbird_A31_defconfig b/configs/Hummingbird_A31_defconfig
index 83f2004..5af42e0 100644
--- a/configs/Hummingbird_A31_defconfig
+++ b/configs/Hummingbird_A31_defconfig
@@ -16,4 +16,5 @@
 CONFIG_CMD_GPIO=y
 CONFIG_ETH_DESIGNWARE=y
 CONFIG_AXP_ALDO1_VOLT=3300
+CONFIG_SYS_NS16550=y
 CONFIG_USB_EHCI_HCD=y