irqchip/gic-v3: Fix priority comparison when non-secure priorities are used

When non-secure priorities are used, compared to the raw priority set,
the value read back from RPR is also right-shifted by one and the
highest bit set.

Add a macro to do the modifications to the raw priority when doing the
comparison against the RPR value. This corrects the pseudo-NMI behavior
when non-secure priorities in the GIC are used. Tested on 5.10 with
the "IPI as pseudo-NMI" series [1] applied on MT8195.

[1] https://lore.kernel.org/linux-arm-kernel/1604317487-14543-1-git-send-email-sumit.garg@linaro.org/



Fixes: 33678059 ("irqchip/gic-v3: Support pseudo-NMIs when SCR_EL3.FIQ == 0")
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
[maz: Added comment contributed by Alex]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210811171505.1502090-1-wenst@chromium.org