usb: ehci-omap: Drop surplus include

The EHCI OMAP driver includes <linux/gpio.h> but does not use
any symbols from this file, so drop it.

Cc: Roger Quadros <rogerq@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20200703131059.515436-1-linus.walleij@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>