[media] ivtv: fix support for big-endian systems

base_addr has type resource_size_t, which may be 64 bits on a 32-bit ppc.

Tested on my ppc board.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>