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/sbc8548_PCI_66_defconfig b/configs/sbc8548_PCI_66_defconfig
index d601416..132e66d 100644
--- a/configs/sbc8548_PCI_66_defconfig
+++ b/configs/sbc8548_PCI_66_defconfig
@@ -3,3 +3,4 @@
 CONFIG_TARGET_SBC8548=y
 CONFIG_SYS_EXTRA_OPTIONS="PCI,66"
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_SYS_NS16550=y