irqchip/jcore-aic: Add J-Core AIC driver

There are two versions of the J-Core interrupt controller in use, aic1
which generates interrupts with programmable priorities, but only
supports 8 irq lines and maps them to cpu traps in the range 17 to 24,
and aic2 which uses traps in the range 64-127 and supports up to 128
irqs, with priorities dependent on the interrupt number. The Linux
driver does not make use of priorities anyway.

For simplicity, there is no aic1-specific logic in the driver beyond
setting the priority register, which is necessary for interrupts to
work at all. Eventually aic1 will likely be phased out, but it's
currently in use in deployments and all released bitstream binaries.

Signed-off-by: Rich Felker <dalias@libc.org>
Link: https://lkml.kernel.org/r/c3b89ef74aaa6477575dbe2d410eb1d182503243.147018b6529.git.dalias@libc.org
Signed-off-by: Jason Cooper <jason@lakedaemon.net>