gpio: davinci: remove unused variable intc_irq_num

As the davinci-gpio driver is migrated to use irqdomain
there is no need to pass the irq base for the gpio driver.
This patch removes this variable from davinci_gpio_platform_data
and also the refrences from the machine file.

Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>