ARM: dts: mvebu: Add PWM properties to .dtsi files

ARM: dts: mvebu: Add PWM properties to .dtsi files

Add properties to the GPIO nodes for Armada 370/XP to allow them to be
also used as PWM lines.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
URL: https://patchwork.ozlabs.org/patch/427294/
[Ralph Sennhauser: Add new compatible string marvell,armada-370-gpio]
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>