V4L/DVB (6677): Fix xc2028 driver for non OFDM

A previous patch implemented support for non-OFDM digital TV. However, the
previous bandwidth ofdm parameter were left at the code by mistake.

Thanks to Michael Krufky and Patrick Boettcher for noticing this mistake.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>