Ho, i see. I’ve never used those kind of LEDs.
It seems that a previous version of OSMC had bugs with spidev (cf. /dev/spidev0.0 missing after 2015.07 update - #15 by duri). Be sure to update to the last one (My OSMC → Updater → Manual Controls → Check for Updates).
How many LEDs do you have ? Power out on Raspberry is limited, so if you have too much LEDs on it, this might be the problem.