pinctrl/lantiq: introduce new dedicated devicetree bindings

This patch introduces new dedicated "lantiq,<chip>-pinctrl" devicetree
bindings, where <chip> is one of "ase", "danube", "xrx100", "xrx200" or
"xrx300" and marks the "lantiq,pinctrl-xway", "lantiq,pinctrl-ase" and
"lantiq,pinctrl-xr9" bindings as DEPRECATED.

Based on the newest Lantiq Hardware Description it turend out, that there are
some differences in the GPIO alternative functions of the Danube, xRX100 and
xRX200 families, which makes it impossible to use only one xway_mfp table.

This patch also adds support for the xRX300 family.

Signed-off-by: Martin Schiller <mschiller@tdt.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>