media: xilinx: regroup caps on querycap

To better organize the code we concentrate the setting of
V4L2_CAP_STREAMING in one place.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>