qcacld-3.0: Drop duplicate auth/assoc frames

Currently duplicate authentication frames are dropped if the
sequence number is same previously processed auth frame and retry
bit is set. To stop the flooding of auth frames with same sequence
number, check the previous seq number stored on the preauth node
and drop if the frame is a duplicate.

Currently, for PMF-capable peers the duplicate assoc request
frames are getting processed before the key is plumbed because
the is_key_installed flag is not reset properly before assigning
the dp hash node to a new sta. Therefore, reset the is_key_installed
flag for every new dp hash node addition.

Change-Id: Id035a5ba5ffe9b745361956d05496f9905bf2526
CRs-Fixed: 3155517