qcacld-3.0: Destroy tx_frm_download_comp_event in wma_close
qcacld-2.0 to qcacld-3.0 propagation
Currently tx_frm_download_comp_event is used in Mcthread and destroyed
in wma_stop, when wma_stop is called, Mcthread has not exited yet.
In stress test, this event is destoryed but Mcthread is still using,
so crash occurs.
Solution is that destroy event in wma_close to avoid the case that after
destroy this event is still used.
Change-Id: I7d4e97ab261f586edfb90268544a2cda4e90a0b2
CRs-Fixed: 958906