[media] dvb: negative value assigned to unsigned int in CDRXD()

In CDRXD(), Negative number is assigned to unsigned variable
'state->noise_cal.tdCal2.

Members of 'SNoiseCal' should be 'signed short'.

Signed-off-by: Santosh Nayak <santoshprasadnayak@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>