serial: 8250_omap: Remove unused of_gpio.h

of_gpio.h is deprecated and subject to remove.
The driver doesn't use it, simply remove the unused header.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240307114048.3642642-1-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_omap.c

@@ -19,7 +19,6 @@
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/of.h>
-#include <linux/of_gpio.h>
 #include <linux/of_irq.h>
 #include <linux/delay.h>
 #include <linux/pm_runtime.h>