panel-mapphone: Change the way mapphone_esd_work checks if the display is on/off.

    Some Defy/Milestone displays seem to not have D7 set while others do.
    This patch makes mapphone_esd_work simply ignore D7 (Step up circuit Voltage Status).

    We should try to find out if D7 should have 1 on ALL displays or if it's
    fine that some don't have that bit set.

    Change-Id: If1aef2a3765d1f8e39fa24031f2232b9aa330e00