When a device uses the GIC as its interrupt controller and generates
SPIs, only the values 1 (edge rising) and 4 (level high) are legal.

Anything else is just plain wrong (can't be programmed into the HW),
and leads to aborted driver probes (USB doesn't work with 4.8-rc1
on a Dragonboard 410C).
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>