Pinky boards don't have the hotplug pin connected. So remove the
hotplug pinctrl setting and enable the force-hpd option, to allow
them to find the display too.

While on speedy boards, the hotplug pin is connected, judging by comments
in a chromeos change it seems the "panels HPD voltage is too low to be
detected", so it also needs the forced hotplug, as we of course also know
that a display is connected.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Douglas Anderson <dianders@chromium.org>