fixes a bug in the snd-bcm2835 driver

The "instance" field of bcm2835_alsa_stream_t may be accessed uninitialized
by bcm2835_audio_set_ctls_chan if called during stream creation. This fix
deferres the addition to of the stream to chip untill it has been fully
initialized.
V4L2: Correct flag settings for compressed formats

Set flags field correctly on enum_fmt_vid_cap for compressed
image formats.

Signed-off-by: Dave Stevenson <dsteve@broadcom.com>