pinctrl: ocelot: Fix GPIO interrupt decoding on Jaguar2

pinctrl: ocelot: Fix GPIO interrupt decoding on Jaguar2

[ Upstream commit 0b47afc65453a70bc521e251138418056f65793f ]

This fixes a problem with using the GPIO as an interrupt on Jaguar2
(and similar), as the register layout of the platforms with 64 GPIO's
are pairwise, such that the original offset must be multiplied with
the platform stride.

Fixes: da801ab56ad8 pinctrl: ocelot: add MSCC Jaguar2 support.
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
Link: https://lore.kernel.org/r/20200513125532.24585-4-lars.povlsen@microchip.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>