[media] bttv: rename struct card_ir to bttv_ir

bttv_ir is more consistent with all other structs used in the same driver.
Also, clean up the struct to remove commented out members and the work_struct
which is unused.

[mchehab@redhat.com: fix a warning at bttv_rc5_timer_end]
Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>