wlan: Post set_key msg to lim with high priority

After EAPOL M4 frame is sent, ADDBA request is received
due to which set_key request processing is delayed in lim.
Encrypted data frames are received from AP before set_key
request is sent to firmware causing DPU errors. This will
result in get_stats and set_key requests not getting
processed and consequently WDI command timeout.

Fix is to post set_key msg with high priority and
drop ADDBA request received before keys are installed

Change-Id: Ie68d42948b9f484d4d7b1664e770127776eecee7
CRs-Fixed: 2293975