omxil: bcm: h264: Don't wait for error free frame.

The bcm h264 decoder is not able to detect when the first error free frame has
been decoded for certain h264 streams. To avoid not getting any frames out of
the decoder, disable the StartWithValidFrame flag until that is fixed at bcm.
See https://github.com/huceke/omxplayer/issues/96 for details.

Signed-off-by: Julian Scheel <julian@jusst.de>