[media] lirc_zilog: Split struct IR into structs IR, IR_tx, and IR_rx

This change is a mostly mechanical break of the main struct IR
data structure into common, Rx, and Tx structures.  There were some
small logical changes required as well, such as eliminating "is_hdpvr",
to accomplish this.

This change is an intiial step in reworking lirc_zilog to decouple the
Rx and Tx handling as much as possible to fit with the new I2C
binding model.  This change actually makes lirc_zilog a little more
broken than it already was - memory deallocation in particular got worse.
However, this change makes the remaining problems easier to see and address.

Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>