ath6kl: Fix merge error in ath6kl_set_ies()

Portion of the commit id 080eec4f ("ath6kl: Clear the IE in firmware
if not set") was overwritten by mistake due to a merge
conflict. This patch fixes the code back to how it should be.

kvalo: more details to the commit log

Signed-off-by: Aarthi Thiruvengadam <athiruve@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>