irqchip/gic: Correctly validate OF quirk descriptors

When checking for OF quirks, make sure either 'compatible' or 'property'
is set, and give up otherwise.

This avoids non-OF quirks being randomly applied as they don't have any
of the OF data that need checking.

Cc: Douglas Anderson <dianders@chromium.org>
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: 44bd78dd ("irqchip/gic-v3: Disable pseudo NMIs on Mediatek devices w/ firmware issues")
Signed-off-by: Marc Zyngier <maz@kernel.org>