ARM: mxs: tx28: reset fec phy for device tree boot

For non-DT boot, function tx28_add_fec0 configures all ENET0 pins
into gpio mode for resetting fec phy, and then reconfigures those pins
into ENET function after that.

For DT boot, all the pin configuration is done by pinctrl subsystem.
Ideally, when gpio_request gets called, GPIO subsystem should call
pinctrl to configure pins into gpio mode automatically, and have pins
freed up from pinctrl subsystem when gpio_free is called.  But right
now, this cooperation between gpio and pinctrl hasn't been available.
As the result, we have to explicitly call pinctrl_get_select and
pinctrl_put for device tree boot.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Lothar Waßmann <LW@KARO-electronics.de>