ARM: dts: armada-38x: Fix compatible string for gpios

Armada 38x supports per CPU interrupts for gpios, like Armada XP. Pre-XP
variants like Armada 370 do not support per CPU interrupts for gpios.

So change compatible string for Armada 38x from "marvell,armada-370-gpio"
which indicates pre-XP variant to "marvell,armadaxp-gpio" which indicates
XP variant or new.

Driver gpio-mvebu.c which handles both pre-XP and XP variants already
provides support for per CPU interrupts on XP and newer variants.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 7cb2acb3 ("ARM: dts: mvebu: Add PWM properties for armada-38x")
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>