V4L/DVB (4604): Fix broken pvrusb2 build

Fix broken build when 24XXX support is not selected.  This is required
due to the requirement of removing 24XXX ifdef's from the driver
source.

Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>