gpiolib: irqchip: prevent driver unloading if gpio is used as irq only

Now nothing prevents GPIO driver from being unloaded if its gpios
were requested as GPIO IRQs only (without calling gpio_request()).

Hence, add calls of try_module_get()/module_put() into
gpiochip_irq_reqres/relres() to track such scenario properly.

Cc: Johan Hovold <johan@kernel.org>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>