[media] stb0899: Fix slow and not locking DVB-S transponder(s)

In stb0899_status stb0899_check_data the first read of STB0899_VSTATUS
could read old (from previous search) LOOP status bit and the search
fails on a good frequency.

With the patch more transponder could be locked and locks about 2*
faster.

Signed-off-by: Lutz Sammer<johns98@gmx.net>
Reviewed-by: Manu Abraham<manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>