media: af9015: enhance streaming config

Replace static stream settings by one which enables and disables
stream interface when needed (TS streaming control).

1) Configure both TS IF and USB endpoints according to current use case

2) Disable streaming USB endpoints when streaming is stopped and
enable when streaming is started. Reduces sleep power consumption
slightly.

3) Reduce USB buffersize slightly, from 130848 to 98136 bytes

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>