media: allegro: rename stream_id to dst_handle

The dst_handle field in the PUT_STREAM_BUFFER and ENCODE_FRAME_RESPONSE
is used to retrieve the V4L2 CAPTURE buffer. Calling it stream_id is
confusing. Call it dst_handle inspired by src_handle for the OUTPUT
buffer.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>