rtl2832_sdr driver implements own USB streaming for SDR data.
Logically that functionality belongs to USB interface driver, but
currently it is implemented here.
Reported-by: kbuild test robot <fengguang.wu@intel.com> Signed-off-by: Antti Palosaari <crope@iki.fi> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>