V4L/DVB (8479): tveeprom/ivtv: fix usage of has_ir field

has_ir was set to and compared to -1 in several cases, even though it is
an u32. ivtv also contained a FIXME for an old kernel that could be
removed.

Thanks to Roel Kluin for creating an initial patch for this. Although
I chose a different solution here it did help in pointing out the problem.

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