serial: 16550: Make serial_io/out_shift available to debug mode

The ns16550 driver needs serial_in_shift() and serial_out_shift()
when compiled in debug UART mode, so shift the DM_SERIAL check a
little to make these functions available.
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: NTom Rini <trini@konsulko.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

drivers/serial/ns16550.c

@@ -54,12 +54,6 @@ DECLARE_GLOBAL_DATA_PTR;
 #define CONFIG_SYS_NS16550_IER  0x00
 #endif /* CONFIG_SYS_NS16550_IER */
 
-#ifdef CONFIG_DM_SERIAL
-
-#ifndef CONFIG_SYS_NS16550_CLK
-#define CONFIG_SYS_NS16550_CLK  0
-#endif
-
 static inline void serial_out_shift(void *addr, int shift, int value)
 {
 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
@@ -94,6 +88,12 @@ static inline int serial_in_shift(void *addr, int shift)
 #endif
 }
 
+#ifdef CONFIG_DM_SERIAL
+
+#ifndef CONFIG_SYS_NS16550_CLK
+#define CONFIG_SYS_NS16550_CLK  0
+#endif
+
 static void ns16550_writeb(NS16550_t port, int offset, int value)
 {
 	struct ns16550_platdata *plat = port->plat;