[media] e4000: implement DC offset correction
[media] e4000: implement DC offset correction

I did some tests against modulator (television signal generator) and this
seems to improve sensitivity a little bit on channel I used. Used device
was able to receive transmission just as weak signal as with Windows XP.
Thanks to Jacek for donating his non-working device. I cannot ask he to
test anymore...

Reported-by: Jacek Konieczny <9288fc269c584d9a40c872c8699e3e1e9e462300@jajcus.net>
Signed-off-by: Antti Palosaari <293134fe763ce2d9d8609280ea107c73cbd2eb86@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <0cae1d1e981e84d16b82ca3d17be8a7f826608d3@samsung.com>

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