serial: ns16550: Add support for SPL_DEBUG_UART_BASE

Use CONFIG_VAL(DEBUG_UART_BASE) instead of CONFIG_DEBUG_UART_BASE, so
proper config value (CONFIG_DEBUG_UART_BASE or CONFIG_SPL_DEBUG_UART_BASE)
is used based on building target.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index a4220fd..78bfe62 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -325,7 +325,7 @@
 
 static inline void _debug_uart_init(void)
 {
-	struct ns16550 *com_port = (struct ns16550 *)CONFIG_DEBUG_UART_BASE;
+	struct ns16550 *com_port = (struct ns16550 *)CONFIG_VAL(DEBUG_UART_BASE);
 	int baud_divisor;
 
 	/*
@@ -360,7 +360,7 @@
 
 static inline void _debug_uart_putc(int ch)
 {
-	struct ns16550 *com_port = (struct ns16550 *)CONFIG_DEBUG_UART_BASE;
+	struct ns16550 *com_port = (struct ns16550 *)CONFIG_VAL(DEBUG_UART_BASE);
 
 	while (!(serial_din(&com_port->lsr) & UART_LSR_THRE)) {
 #ifdef CONFIG_DEBUG_UART_NS16550_CHECK_ENABLED