ARM: davinci: board: gpio device creation

Create GPIO device for existing DaVinci boards.

While at it, group related header files together.

Signed-off-by: Philip Avinash <avinashphilip@ti.com>
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
[nsekhar@ti.com: remove soc bits from this patch and
		 simplify commit message]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>