serial: liteuart: use bit number macros

Replace magic bit constants (e.g., 1, 2, 4) with BIT(x) expressions.
Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20221123130500.1030189-3-gsomlo@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/liteuart.c

@@ -5,6 +5,7 @@
  * Copyright (C) 2019-2020 Antmicro <www.antmicro.com>
  */
 
+#include <linux/bits.h>
 #include <linux/console.h>
 #include <linux/litex.h>
 #include <linux/module.h>
@@ -38,8 +39,8 @@
 #define OFF_EV_ENABLE	0x14
 
 /* events */
-#define EV_TX		0x1
-#define EV_RX		0x2
+#define EV_TX		BIT(0)
+#define EV_RX		BIT(1)
 
 struct liteuart_port {
 	struct uart_port port;