rtc: omap: drop unused dt-bindings header

The definitons in the dt-binding's gpio header only contains some
constants to be used in device trees. It is not relevant for rtc-omap
(as the gpio API hides the details) and in fact unused so it can just be
dropped.
Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20200321203737.29850-1-uwe@kleine-koenig.orgSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-omap.c

@@ -9,7 +9,6 @@
  * Copyright (C) 2014 Johan Hovold <johan@kernel.org>
  */
 
-#include <dt-bindings/gpio/gpio.h>
 #include <linux/bcd.h>
 #include <linux/clk.h>
 #include <linux/delay.h>