[PATCH] ns16550: Properly gate Exar PCIe UART cards support

[Oleksandr Andrushchenko <andr2000@xxxxxxxxx>]

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>

This fixes Arm build which doesn't have ns16550 PCI support.

ns16550.c:313:5: error: implicit declaration of function 
'enable_exar_enhanced_bits' [-Werror=implicit-function-declaration]
  313 |     enable_exar_enhanced_bits(uart);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 5ffd37db2ff6 ("ns16550: add Exar PCIe UART cards support")

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
---
 xen/drivers/char/ns16550.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index b777c8711ee0..e2c24082c368 100644
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -308,7 +308,7 @@ static void ns16550_setup_preirq(struct ns16550 *uart)
     /* Handle the DesignWare 8250 'busy-detect' quirk. */
     handle_dw_usr_busy_quirk(uart);
 
-#ifdef CONFIG_HAS_PCI
+#ifdef NS16550_PCI
     /* Enable Exar "Enhanced function bits" */
     enable_exar_enhanced_bits(uart);
 #endif
-- 
2.25.1