[media] media: dvb_core: replace a magic number by a macro

It's better to use TS_SC instead of magic number 0xC0.

[m.chehab@samsung.com: patch rebased and message rewritten, as this
 patch conflicted with an already applied patch]

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>