fix OMAP_DSS_MANAGER for kernels >= 3.11

see linux commit a73fdc647417699833f22d0f239affe22e062827
Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
Date:   Wed Jul 24 13:01:34 2013 +0300

    OMAPDSS: rename omap_dss_device's 'output' to 'src'

    In the old panel device model we had "outputs", which were the encoders
    inside OMAP DSS block, and panel devices (omap_dss_device). The panel
    devices had a reference to the source of the video data, i.e. reference
    to an "output", in a field named "output".

    That was somewhat confusing even in the old panel device model, but even
    more so with the panel device model where we can have longer chains of
    display entities.

    This patch renames the "output" field to "src", which much better tells
    what the field points to.

    Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
    Reviewed-by: Archit Taneja <archit@ti.com>

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>