Desire Z and Desire HD use OMX_COLOR_FormatYUV420SemiPlanar,
which when inspected turns out to be NV12, while Nexus One
either reports OMX_QCOM_COLOR_FormatYVU420SemiPlanar (or
falsely reports OMX_COLOR_FormatYUV420Planar) which is NV21.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>