gpio: omap: Fix regression for MPUIO interrupts

gpio: omap: Fix regression for MPUIO interrupts

At some point with all the GPIO clean-up we've broken the
MPUIO interrupts. Those are just a little bit different from
the GPIO interrupts, so we can fix it up just by setting
different irqchip functions for it. And then we can just
remove all old code trying to do the same.

Cc: Aaro Koskinen <[email protected]>
Cc: Javier Martinez Canillas <[email protected]>
Cc: Kevin Hilman <[email protected]>
Cc: Nishanth Menon <[email protected]>
Signed-off-by: Tony Lindgren <[email protected]>
Reviewed-by: Grygorii Strashko <[email protected]>
Acked-by: Santosh Shilimkar <[email protected]>
Reviewed-by: Felipe Balbi <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>