[media] stb0899: use autodetected inversion instead of configured inversion

For consistency, it is necessary to use the autodetected inversion
instead of the configured one.

Signed-off-by: Reinhard Nißl <rnissl@gmx.de>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>