Now that irq_domain_simple_ops are available for non-DT users, use them
in the VIC driver so that we don't get a NULL dereference in
irq_domain_to_irq() when registering the domain.

Cc: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>