V4L/DVB (10287): af9015: fix second FE

Bug causes 2nd FE MPEG TS buffer size to be zero and therefore no picture
when 2nd FE was enabled. Configure correct buffer size also for 2nd FE.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>