[ARM] S3C24XX: GPIO: Move gpio functions out of <mach/hardware.h>

Move all the gpio functions out of <mach/hardware.h> as
this file is for defining the generic IO base addresses
for the kernel IO calls.

Make a new header <mach/gpio-fns.h> to take this and
include it via the chain from <linux/gpio.h> which is
what most of these files should be using (and will be
changed as soon as possible).

Note, this does make minor changes to some drivers but
should not mess up any pending merges.

CC: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
CC: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>