altera_uart: Adjust the declaration of debug_uart_init()

Follow commit 97b0597302 ("debug_uart: Adjust the declaration of
debug_uart_init()")

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Chin Liang See <clsee@altera.com>

drivers/serial/altera_uart.c

@@ -124,7 +124,7 @@ U_BOOT_DRIVER(altera_uart) = {
 
 #include <debug_uart.h>
 
-void debug_uart_init(void)
+static inline void _debug_uart_init(void)
 {
 	struct altera_uart_regs *regs = (void *)CONFIG_DEBUG_UART_BASE;
 	u32 div;