V4L/DVB (10987): cx23885: fix crash on non-netup cards

The new support for the CX23885_BOARD_NETUP_DUAL_DVBS2_CI board broke the
existing boards. Interrupts for the netup part were enabled and handled
without testing whether the current board actually had a netup -> instant
and fatal crash.

I've added tests to do this only for the CX23885_BOARD_NETUP_DUAL_DVBS2_CI
board.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Reviewed-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>