Keep it set to whatever the codec had set it to initially.

This makes the IOMX codecs work on Nexus 7.

This might also help for issues on Qualcomm devices (buffer sizes
that were too large on Nexus One, but restricting them broke
larger resolutions on HP TouchBook instead).

Optionally, one might need to call OMX_SetParameter/OMX_GetParameter
after setting the width/height to get a proper buffer size initialized
instead.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>