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/sniper_defconfig b/configs/sniper_defconfig
index 7afaa49..0474deb 100644
--- a/configs/sniper_defconfig
+++ b/configs/sniper_defconfig
@@ -6,5 +6,6 @@
 # CONFIG_CMD_IMLS is not set
 # CONFIG_CMD_FLASH is not set
 # CONFIG_CMD_FPGA is not set
+CONFIG_SYS_NS16550=y
 CONFIG_USB=y
 CONFIG_USB_MUSB_GADGET=y