flv: Workaround for buggy Omnia A/XE encoder

The Omnia A/XE encoder writes the explicit extra data incorrectly
and wrongly disables parametric stereo. Truncating the extra data
by setting the size to 2 works around this. The AAC extra data
parser will then only parse the correct parts.

Bug-id: 599
vc1dsp: K&R formatting cosmetics

Signed-off-by: Diego Biurrun <diego@biurrun.de>