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/am335x_boneblack_defconfig b/configs/am335x_boneblack_defconfig
index c5c7b5d..87a320b 100644
--- a/configs/am335x_boneblack_defconfig
+++ b/configs/am335x_boneblack_defconfig
@@ -10,3 +10,4 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_DFU_TFTP=y
 CONFIG_SPI_FLASH=y
+CONFIG_SYS_NS16550=y