drm/i915/edp: get the panel delay before powering up

In order to setup the i2c channel, we power up the panel
via ironlake_edp_panel_vdd_on, however it requires
intel_dp->panel_power_up_delay to be initialised,
which hasn't been setup yet.

So move things around so we set the panel power up
values first then init the i2c stuff.

This is one step to fixing the eDP panel in the MBP
from uninitialised state.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>