Fix segfault in add_ti()

Commit 12553e19c1180551541abbd217eab4e9ed7a511a made `add_ti` in command_mode.c
depend on `data` parameter being non-NULL. At the same time, one case in
`cmd_run` function still called `add_ti` with NULL — which leads to segfault.

Reported-by: @cjsthompson
Signed-off-by: Gregory Petrosyan <gregory.petrosyan@gmail.com>
cdio: make it work with libcdio 0.90+

Signed-off-by: Gregory Petrosyan <gregory.petrosyan@gmail.com>