serial: pl011: Enable DEBUG_UART_PL011 in SPL

Commit b81406db ("arm: serial: Add debug UART capability to the
pl01x driver") add supports to use pl01x as a debug UART. However,
due to CONFIG_IS_ENABLED macro requires CONFIG_SPL_* prefix, the
_debug_uart_init() would not choose TYPE_PL011 in SPL build. This
patch fixes the bug by judging CONFIG_DEBUG_UART_PL011 explicitly.
Signed-off-by: NChen Baozi <chenbaozi@phytium.com.cn>
Reviewed-by: NSimon Glass <sjg@chromium.org>

drivers/serial/serial_pl01x.c

@@ -404,8 +404,12 @@ static void _debug_uart_init(void)
 {
 #ifndef CONFIG_DEBUG_UART_SKIP_INIT
 	struct pl01x_regs *regs = (struct pl01x_regs *)CONFIG_DEBUG_UART_BASE;
-	enum pl01x_type type = CONFIG_IS_ENABLED(DEBUG_UART_PL011) ?
-				TYPE_PL011 : TYPE_PL010;
+	enum pl01x_type type;
+
+	if (IS_ENABLED(CONFIG_DEBUG_UART_PL011))
+		type = TYPE_PL011;
+	else
+		type = TYPE_PL010;
 
 	pl01x_generic_serial_init(regs, type);
 	pl01x_generic_setbrg(regs, type,