gpio: Rename func/macro/var to IP-block,iproc

Change functions, macros and variables name from cygnus to IP block,
iproc, so that it could be used in all iproc based future SoCs having
same GPIO controller block.

Signed-off-by: Pramod Kumar <pramodku@broadcom.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>