Since v3.18, attempts to deliver IRQ0 are rejected, breaking orion5x.
Fix this by increasing all interrupts by one, as did 5d6bed2a for
dove. Also, force MULTI_IRQ_HANDLER for all orion platforms (including
dove) as the specific handler is needed to shift back IRQ numbers by
one.

[gregory.clement@free-electrons.com]: moved the select
MULTI_IRQ_HANDLER from PLAT_ORION_LEGACY to ARCH_ORION5X as it broke
the build for dove.

Fixes: a71b092a ("ARM: Convert handle_IRQ to use __handle_domain_irq")
Signed-off-by: Benjamin Cama <benoar@dolka.fr>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Cc: <stable@vger.kernel.org>
Tested-by: Detlef Vollmann <dv@vollmann.ch>