board: nuvoton: update console environment variable

If CONFIG_SYS_SKIP_UART_INIT is enabled, calculate the
current baud rate and update the "console" environment
variable.

Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
diff --git a/board/nuvoton/common/Makefile b/board/nuvoton/common/Makefile
new file mode 100644
index 0000000..8fd83b2
--- /dev/null
+++ b/board/nuvoton/common/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SYS_SKIP_UART_INIT)	+= uart.o