V4L/DVB (7342): saa7115: fix PAL-Nc handling

Fsc 3.58 refers to Combination PAL-N (aka PAL-Nc), not to plain PAL-N (that
uses Fsc 4.43).

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>