altera_jtag_uart: Adjust the declaration of debug_uart_init()

Follow commit 97b059730218 ("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_jtag_uart.c

@@ -130,7 +130,7 @@ U_BOOT_DRIVER(altera_jtaguart) = {
 
 #include <debug_uart.h>
 
-void debug_uart_init(void)
+static inline void _debug_uart_init(void)
 {
 }