Fix expiration logic for the first PTKSA cache entry

Fix expiration logic for the first PTKSA cache entry

When an entry is added to the PTKSA cache, timer expiration is not set.
Check the list and set the timer expiration when the list is empty also.
When another entry is added to the list, it is placed before the relavant
entry in the order of expiry time of all entries present in the list.

Fixes: a4e36916168a ("WPA: Add PTKSA cache implementation")
Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>