soc: fujitsu: Add A64FX diagnostic interrupt driver

Register the NMI/IRQ corresponding to the A64FX's device definition
dedicated to diagnostic interrupts, so that when this interrupt is
sent using the BMC, it causes a panic. This can be used to obtain
a kernel dump.

Signed-off-by: Hitomi Hasegawa <hasegawa-hitomi@fujitsu.com>
Link: https://lore.kernel.org/r/20220520074119.3574753-2-hasegawa-hitomi@fujitsu.com

'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>