[media] airspy: enhance sample rate debug calculation precision
[media] airspy: enhance sample rate debug calculation precision

Sample rate calculation gives a little bit too large results because
in real life there was around one milliseconds (~one usb packet) too
much data for given time. Calculate time more accurate in order to
provide better results.

Signed-off-by: Antti Palosaari <293134fe763ce2d9d8609280ea107c73cbd2eb86@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <ad86ba2154032c9f55743a190faa2459a9d61d42@osg.samsung.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs