[media] si2168: firmware download fix

First 8 bytes belonging to firmware image were hard-coded and uploaded
by the driver mistakenly. Introduce new corrected firmware file and
remove those 8 bytes from the driver.

New firmware image could be extracted from the PCTV 292e driver CD
using following command:

$ dd if=/TVC 6.4.8/Driver/PCTV Empia/emOEM.sys ibs=1 skip=1089408 count=2728 of=dvb-demod-si2168-02.fw
$ md5sum dvb-demod-si2168-02.fw
d8da7ff67cd56cd8aa4e101aea45e052  dvb-demod-si2168-02.fw
$ sudo cp dvb-demod-si2168-02.fw /lib/firmware/

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>