Input: hp_sdc_rtc - unlock on error in hp_sdc_rtc_read_i8042timer()

The transaction task here is hp_sdc_tasklet() and it releases the lock.
The problem is if we aren't able to queue the transaction then we need
to release the lock ourselves.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>