lantiq: Backport upstream pinctrl-xway patches from 4.5

lantiq: Backport upstream pinctrl-xway patches from 4.5

Upstream commit be14811c03cf2 "pinctrl/lantiq: introduce new dedicated
devicetree bindings" allows us to use each pin in the pinmux. This is
useful for example in the "spi" group which contains some pins which
are inputs, and some which are outputs.
These can only be used once the new compatible strings for the pinctrl
node are used.
Additionally 0150-lantiq-pinctrl-xway.patch and the "GPIO PORT3 fix"
(which was part of 0012-pinctrl-lantiq-fix-up-pinmux.patch) were
replaced with their upstream variants which are also in 4.5.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@48283 3c298f89-4303-0410-b956-a3cf2f4a3e73