qcacld-3.0: Fix memzero of key_params in wma_set_stakey

In wma_set_stakey key_params is memset to 0 in first loop for num_key
while being used in subsequent loops for num_key.
So with key_params all zero the vdev id used to send for next key is
always 0.

So memset key_params after loop before returning from wma_set_stakey.

Change-Id: I3990a5c5017f068bb41914c6e38c4e8c2155bb19
CRs-Fixed: 2441622