Currently FASTREASSOC issues roam command to trigger fw process
LFR3 roaming. When roam event comes back, it deletes the old pe
session and creates a new one hence the bss desc info is lost.
Funtion lim_is_medium_time_valid could not get desc info and
cause addTS fail.
To resolve this issue, store the wmm info in the pe session if
it presents.
Change-Id: I6c7c79c96fed7384a686a1fa0f49069440096e90
CRs-Fixed: 3058801
c375bc51a8