V4L/DVB: cx23885: Convert from struct card_ir to struct cx23885_ir_input for IR Rx

Move from the generic, shared card_ir state structure to a cx23885 driver
specific IR state structure in anticipation of moving to the new IR pulse
decoders in the IR core.

Fix up the card name truncation in the dmesg log while we're at it,
by avoiding using fixed length string storage in our new IR state
structure.

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