pinctrl: mvebu: orion5x: Generalise mv88f5181l support for 88f5181

As far as I'm aware the mv88f5181-b1 and mv88f5181l are the same at the
pinctrl level, so re-use the definitions for both.

[gregory.clement@free-electrons.com: fix commit title]
Signed-off-by: Jamie Lentin <jm@lentin.co.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>