gpio: davinci: reuse for keystone soc

The similar GPIO HW block is used by keystone SoCs as
in Davinci SoCs.
Hence, reuse Davinci GPIO driver for Keystone taking into
account that Keystone contains ARM GIC IRQ controller which
is implemented using IRQ Chip.

Documentation:
	http://www.ti.com/lit/ug/sprugv1/sprugv1.pdf



Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>