gpio: davinci: coding style correction

Make some minor coding style fixes. Use proper multi-line
commenting style, and use a macro for register offset.

Signed-off-by: Philip Avinash <avinashphilip@ti.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
[nsekhar@ti.com: drop changes which are considered
		 unnecessary churn - line break fixes
		 variable name changes and include file
		 reordering]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>