pinctrl: mvebu: add additional variant for standalone CP115

pinctrl: mvebu: add additional variant for standalone CP115

With CP115 standalone modules, all MPP configuration are
possible. Handle this new possibility thanks to the new
"marvell,cp115-standalone-pinctrl" compatible property.

Signed-off-by: Grzegorz Jaszczyk <jaz@semihalf.com>
[<miquel.raynal@bootlin.com>: mention the new compatible in the
commit log]
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20190805101607.29811-4-miquel.raynal@bootlin.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>