net: mediatek: Explicitly include pinctrl headers

The Mediatek ethernet driver fails to build after commit 23c35f48


("pinctrl: remove include file from <linux/device.h>") because it relies
on the pinctrl/consumer.h and pinctrl/devinfo.h being pulled in by the
device.h header implicitly.

Include these headers explicitly to avoid the build failure.

Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>