serial: Replace CONFIG_DEBUG_UART_BASE by CONFIG_VAL(DEBUG_UART_BASE)

CONFIG_VAL(DEBUG_UART_BASE) expands to CONFIG_DEBUG_UART_BASE or
CONFIG_SPL_DEBUG_UART_BASE or CONFIG_TPL_DEBUG_UART_BASE and allows boards
to set different values for SPL, TPL and U-Boot Proper.

For ns16550 driver this support is there since commit d293759d55cc
("serial: ns16550: Add support for SPL_DEBUG_UART_BASE").

Signed-off-by: Pali Rohár <pali@kernel.org>
diff --git a/drivers/serial/serial_stm32.c b/drivers/serial/serial_stm32.c
index f6cb708..2ba92bf 100644
--- a/drivers/serial/serial_stm32.c
+++ b/drivers/serial/serial_stm32.c
@@ -270,7 +270,7 @@
 
 static inline void _debug_uart_init(void)
 {
-	fdt_addr_t base = CONFIG_DEBUG_UART_BASE;
+	fdt_addr_t base = CONFIG_VAL(DEBUG_UART_BASE);
 	struct stm32_uart_info *uart_info = _debug_uart_info();
 
 	_stm32_serial_init(base, uart_info);
@@ -281,7 +281,7 @@
 
 static inline void _debug_uart_putc(int c)
 {
-	fdt_addr_t base = CONFIG_DEBUG_UART_BASE;
+	fdt_addr_t base = CONFIG_VAL(DEBUG_UART_BASE);
 	struct stm32_uart_info *uart_info = _debug_uart_info();
 
 	while (_stm32_serial_putc(base, uart_info, c) == -EAGAIN)