veyron jaq, jerry, minnie and speedy have mostly redundant regulator
and pinctrl configurations for the panel/backlight. Consolidate these
pieces in the eDP .dtsi.

Also change the default power supply for the panel to
'panel_regulator', instead of overriding it in all the board files.
pinky is the only device that uses 'vcc33_lcd' (the prior default),
so overwrite it in this case. pinky doesn't have a complete display
configuration, to keep things as they were delete the common nodes
that didn't exist previously in pinky's board file.
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>