block: fix comment to use set_current_state

The explanatory comment used `set_task_state` instead of
`set_current_state` which is the function actually used in the code.

Signed-off-by: Alvaro Parker <alparkerdf@gmail.com>
Link: https://lore.kernel.org/r/20240903172214.520086-1-alparkerdf@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>