Block device LED trigger.

Make a read/write/readwrite LED trigger for each block device.
Fix memleak.
ledtrig-block: switch to 'advanced' register interface.
Add led trigger activation callbacks.

Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Fix parameter.

Signed-off-by: Michal Suchanek <hramrach@gmail.com>
Fix segfault.
Fix segfault.
Remove ide disk trigger.