irqchip: Port the ARM IRQ drivers to GENERIC_IRQ_MULTI_HANDLER

GENERIC_IRQ_MULTI_HANDLER is incompatible with MULTI_IRQ_HANDLER because
they define the same symbols.  Multiple generic irqchip drivers select
MULTI_IRQ_HANDLER, which is now defined on all architectures that
provide set_handle_irq().

To solve this select GENERIC_IRQ_MULTI_HANDLER for all drivers that used to
select MULTI_IRQ_HANDLER, but only when MULTI_IRQ_HANDLER doesn't exist.

After that every architecture can be converted over from MULTI_IRQ_HANDLER
to GENERIC_IRQ_MULTI_HANDLER before removing the extra MULTI_IRQ_HANDLER
scaffolding.

Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux@armlinux.org.uk
Cc: catalin.marinas@arm.com
Cc: Will Deacon <will.deacon@arm.com>
Cc: jonas@southpole.se
Cc: stefan.kristiansson@saunalahti.fi
Cc: shorne@gmail.com
Cc: jason@lakedaemon.net
Cc: marc.zyngier@arm.com
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: nicolas.pitre@linaro.org
Cc: vladimir.murzin@arm.com
Cc: keescook@chromium.org
Cc: jinb.park7@gmail.com
Cc: yamada.masahiro@socionext.com
Cc: alexandre.belloni@bootlin.com
Cc: pombredanne@nexb.com
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: kstewart@linuxfoundation.org
Cc: jhogan@kernel.org
Cc: mark.rutland@arm.com
Cc: ard.biesheuvel@linaro.org
Cc: james.morse@arm.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: openrisc@lists.librecores.org
Cc: Shea Levy <shea@shealevy.com>
Link: https://lkml.kernel.org/r/20180622170126.6308-2-palmer@sifive.com