serial: zynq: Remove duplicated header

debug_uart.h is included twice.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/serial/serial_zynq.c b/drivers/serial/serial_zynq.c
index 6807f0f..b2b98de 100644
--- a/drivers/serial/serial_zynq.c
+++ b/drivers/serial/serial_zynq.c
@@ -192,9 +192,6 @@
 };
 
 #ifdef CONFIG_DEBUG_UART_ZYNQ
-
-#include <debug_uart.h>
-
 void _debug_uart_init(void)
 {
 	struct uart_zynq *regs = (struct uart_zynq *)CONFIG_DEBUG_UART_BASE;