ais: set list cmd to be available after del before return

If clk disabled, we have to set current cmd to be available again
before function return, otherwise the same list member will be
double deleted when do enqueue tasklet next time.

Change-Id: Ibc392169a7e7ad084b14abaaa9cb3c61d06adcf4
Signed-off-by: Andy Sun <bins@codeaurora.org>