um: Add irq chip um/mask handlers
um: Add irq chip um/mask handlers

These handlers are not optional and need in our case
dummy implementions to avoid NULL pointer bugs within
the irq core code.

Reported-and-tested-by: Toralf Foester <24e9a7e86225fc01f236a81fc86e902a74542aa1@gmx.de>
Signed-off-by: Richard Weinberger <320bca71fc381a4a025636043ca86e734e31cf8b@nod.at>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs