V4L/DVB (3807): Cx88-blackbird: fix typo

BLACKBIRD_FIELD1_SAA7115 was repeated.  Corrected version reads:
blackbird_api_cmd(dev, BLACKBIRD_API_SET_CAPTURE_LINES, 2, 0,
                BLACKBIRD_FIELD1_SAA7115,
                BLACKBIRD_FIELD2_SAA7115
)

Thanks-to: Valentin Zagura <puthre@gmail.com> for pointing this out.
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>