pinctrl: generic: Parse pinmux init nodes if node status is okay

During pinmux registration, pinmux table is parsed from DT
for making the pinmux table configuration of pins.

Parse the only those node whose status is not disabled.
This will help on reusing the pin configuration table across
platform and disabling the node by status property if that node
is not needed on given platform.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>