twl4030-gpio: irq and other cleanup

Remove some ARM and OMAP specific stuff from the twl4030 GPIO code,
and some unused/undesirable CPP symbols.  Add minor checkpatch fixes.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>