drm/i915: Flatten intel_edp_panel_vdd_on()

Less pointless indentation is always nice. There will be a bit more
code in this function once the power sequencer locking is fixed.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>